JPH11172016A - Modified polypropylene resin sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a modified polypropylene resin sheet having improved theremoformability as well as rigidity, etc., inherent in the starting polypropylene resin by a simple apparatus and an easy process by using modified polypropylene resin obtained by melt-kneading a polypropylene resin, an isoprene monomer, and a radical polymerization initiator. SOLUTION: The starting polypropylene resin used may be a propylene homopolymer or a block or random copolymer of propylene with another monomer. It is desirable that the weight-average molecular weight of the starting polypropylene is in the range of 50,000-2,000,000 in respect of its industrial availability, desirably, in the range of 100,000-1,000,000 in respect of its inexpensiveness. It is desirable that the isoprene monomer is added in an amount of 0.1-30 pts.wt. per 100 pts.wt. starting polypropylene. The radical polymerization initiator used is usually exemplified by a peroxide or an azo compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet made of a modified polypropylene resin and a molded product obtained by vacuum or pressure forming the sheet. More specifically, a modified polypropylene resin sheet having improved melting properties, excellent workability, exhibiting properties such as rigidity and surface properties, or transparency, and which can be suitably molded into various molded articles, and the like. The present invention relates to a molded article formed by vacuum forming or pressure forming.

[0002]

2. Description of the Related Art Conventionally, polypropylene has been widely used for various molded articles because of its low cost and excellent physical properties. However, since polypropylene has low viscosity and tension at the time of melting, it has drawbacks in terms of processability such as inferior in sheet vacuum formability, air pressure formability (hereinafter referred to as thermoformability), calender moldability, and the like.

For the purpose of improving the processability of the polypropylene, polyethylene and the like are generally mechanically mixed, but the effect of improving the processability is insufficient.
A disadvantage is that a large amount of polyethylene is required, and the rigidity of the resulting mixture is reduced. Attempts have been made to improve the viscosity and tension at the time of melting by increasing the molecular weight of polypropylene. However, polypropylene having a large molecular weight is difficult to extrude, which is one of the important processing methods. There is a big problem that there is.

In order to improve the processability such as thermoformability of the polypropylene, a polyolefin, a methacrylate polymer and a methacrylate obtained by polymerizing a methacrylate monomer in a hydrocarbon solvent in the presence of a polyolefin are grafted. Attempts have been made to add a mixture of the obtained polyolefins to polypropylene (Japanese Patent Laid-Open No. 22316/1990), but in order to sufficiently exhibit such an effect of improving processability, the mixture is required in a large amount. In addition, since the high temperature solution polymerization method is used, there are problems in terms of manufacturing cost and safety. Further, it is necessary to remove the solvent at the time of mixing the polyolefin, and there is a problem that workability and safety are poor.

Japanese Patent Application Laid-Open No. 62-121704 discloses that a semi-crystalline polypropylene resin having a linear molecular structure is irradiated with radiation in a gas atmosphere adjusted to a specific oxygen concentration. Has proposed a method of increasing the viscosity and tensile strength of the polypropylene resin at the time of melting. The patent publication states that the polypropylene resin modified by this method has a structure in which the polymer molecule has a long-chain branch, and this resin is used in a molding method such as blow molding or extrusion coating molding. It is stated that it is suitable.

[0006] The reason that the polypropylene resin modified by this method is suitable for these molding methods is that the elongational viscosity of the resin measured in a molten state is as follows.
That is, it increases rapidly as the amount of strain increases, that is, when the resin is subjected to tensile deformation in a molten state, the elongational viscosity increases as the elongational strain increases,
It is pointed out that the elongational viscosity sharply increases after reaching a specific elongational strain value.

However, when the polypropylene resin is modified by this method, it is inevitable that a large-scale apparatus is used and the structure of the apparatus is complicated in order to utilize radiation. In addition, in the irradiation step, in order to prevent decomposition and gelation of the propylene-based resin and stably produce the product, it is necessary to strictly control the irradiation amount of the radiation and the oxygen concentration of the atmosphere gas. Further, since it is necessary to strictly control the production conditions in this way, it has not been easy to give a variation to the physical properties of the target modified polypropylene resin composition.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a modified polypropylene having improved thermoformability by using a simple apparatus and by an easy method without impairing the inherent characteristics of the polypropylene resin such as rigidity. It is to provide a system resin sheet.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a modified resin obtained by melt-kneading a polypropylene resin, an isoprene monomer and a radical polymerization initiator has been obtained. A sheet made of a polypropylene-based resin is excellent in thermoformability without impairing the inherent characteristics of the polypropylene-based resin, and a sheet in which a nucleating agent is present in the modified polypropylene-based resin has improved processability and transparency. It has finally been found that a sheet in which an inorganic filler is present in a high-quality polypropylene resin exhibits physical properties such as processability, rigidity, and surface properties, and has completed the present invention.

That is, the present invention relates to a sheet made of a modified polypropylene resin obtained by melt-kneading a polypropylene resin, an isoprene monomer and a radical polymerization initiator. The present invention also relates to a molded product obtained by thermoforming the modified polypropylene resin sheet.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The modified polypropylene resin of the present invention comprises a resin obtained by melt-kneading a polypropylene resin, an isoprene monomer and a radical polymerization initiator, so that drawdown during melting hardly occurs. Therefore, the thermoformability is remarkably improved.

The modified polypropylene resin used in the present invention comprises a polypropylene resin (hereinafter, this polypropylene resin may be referred to as “raw material polypropylene resin”), an isoprene monomer, and a radical polymerization initiator. Is kneaded at a temperature at which the resin melts. Examples of the raw material polypropylene-based resin include propylene homopolymer, crystalline polymers such as block copolymers of propylene and other monomers or random copolymers of propylene and other monomers. The rigidity is high, the polypropylene homopolymer is preferable in that it is inexpensive, and the rigidity and impact resistance are both block copolymers of the propylene and other monomers. Is preferred. When the raw material polypropylene-based resin is a block copolymer of propylene and other monomers or a random copolymer of propylene and other monomers, high crystallinity, which is characteristic of polypropylene-based resins, high From the viewpoint of maintaining rigidity and good chemical resistance, the content of the propylene monomer component is preferably at least 75% by weight, more preferably at least 90% by weight.

In the raw material polypropylene resin,
As other monomers copolymerizable with propylene, one or more selected from the group consisting of ethylene, α-olefin, cyclic olefin, diene monomer and vinyl monomer Monomers. Of these monomers, ethylene or butene-1 is preferred because it is inexpensive.

The molecular weight (weight average molecular weight) of the raw material polypropylene resin is preferably in the range of 50,000 to 2,000,000 from the viewpoint of industrial availability, and from 100,000 to 2,000,000 from the viewpoint of low cost. More preferably, it is within the range of 1,000,000. If necessary, another resin or rubber may be added to the raw material polypropylene-based resin as long as the effects of the present invention are not impaired. Examples of the other resin or rubber include polyethylene; poly-α-olefins such as polybutene-1, polyisobutene, polypentene-1, and polymethylpentene-1; ethylene / propylene copolymers having a propylene content of less than 75% by weight; Ethylene / butene-1 copolymer, ethylene or α-olefin / α-olefin copolymer such as propylene / butene-1 copolymer having a propylene content of less than 75% by weight; propylene content of less than 75% by weight Ethylene or α-olefin / α- such as ethylene / propylene / 5-ethylidene-2-norbornene copolymer
Olefin / diene monomer copolymer; ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / methacrylic acid copolymer, ethylene / ethyl acrylate copolymer, ethylene / butyl acrylate copolymer Polymer,
Ethylene / ethylene such as ethylene / methyl methacrylate copolymer, ethylene / maleic anhydride copolymer, ethylene / metal acrylate copolymer, ethylene / metal methacrylate copolymer, ethylene / glycidyl methacrylate copolymer Vinyl monomer copolymer; polydiene copolymer such as polybutadiene and polyisoprene; vinyl monomer such as styrene / butadiene / styrene block copolymer / diene monomer / vinyl monomer block copolymer An acrylonitrile / butadiene / styrene graft copolymer,
Vinyl monomer such as methyl methacrylate / butadiene / styrene graft copolymer / diene monomer / vinyl monomer graft copolymer; polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polyvinyl acetate, polyacryl Vinyl polymers such as ethyl acrylate, polybutyl acrylate, polymethyl methacrylate, and polystyrene; vinyl chloride / acrylonitrile copolymer, vinyl chloride / vinyl acetate copolymer, acrylonitrile / styrene copolymer, methyl methacrylate / styrene copolymer Examples include vinyl copolymers such as polymers.

The amount of the other resin or rubber to be added to the starting polypropylene resin depends on the type of the resin or the type of rubber, and may be within the range that does not impair the effects of the present invention as described above. But usually
It is preferably about 25% by weight or less. The modified polypropylene resin of the present invention is produced by melt-kneading a polypropylene resin, an isoprene monomer, another vinyl monomer copolymerizable with the isoprene monomer, and a radical polymerization initiator. Is also good.

Other vinyl monomers copolymerizable with the isoprene monomer include, for example, vinyl chloride; vinylidene chloride; styrene; acrylonitrile; methacrylonitrile; acrylamide; methacrylamide; vinyl acetate; Maleic acid; maleic anhydride; metal acrylate; metal methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate;
Acrylates such as stearyl acrylate and glycyl acrylate; methacrylates such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, stearyl methacrylate and glycidyl methacrylate;

When the isoprene monomer and another vinyl monomer copolymerizable with the isoprene monomer are used in combination, the amount of the other vinyl monomer copolymerizable with the isoprene monomer is reduced. The amount is preferably 100 parts by weight or less, more preferably 75 parts by weight or less on average with respect to 100 parts by weight of the isoprene monomer. If the amount of the other vinyl monomer copolymerizable with the isoprene monomer exceeds the above range, the viscosity of the obtained modified polypropylene resin is significantly reduced, and the thermoformability may be reduced. .

The amount of the isoprene monomer to be melt-kneaded is preferably from 0.1 to 30 parts by weight, and more preferably from 0.1 to 30 parts by weight, based on 100 parts by weight of the starting polypropylene resin.
More preferably, it is 0 parts by weight. When the amount of the isoprene monomer is less than the above range, the drawdown of the secondary molding sheet made of the objective modified polypropylene resin is large, and there is a case where the thermoformability decreases, while the If it exceeds the range, heat resistance and rigidity, which are characteristics of the polypropylene resin, may be impaired.

The radical polymerization initiator generally includes a peroxide or an azo compound. As the radical polymerization initiator, one or more kinds of organic peroxides such as ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxydicarbonate, peroxyester, and the like are used. can give. Of these,
Particularly, those having high hydrogen abstracting ability are preferable. Examples of such radical polymerization initiators include 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and 1,1-bis (t -Butyl peroxy)
Peroxy ketals such as cyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate and 2,2-bis (t-butylperoxy) butane; dicumyl peroxide, 2,5-dimethyl- 2,5-di (t
-Butylperoxy) hexane, α, α'-bis (t-
Butylperoxy-m-isopropyl) benzene, t-
Dialkyl peroxides such as butylcumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3; diacyl peroxides such as benzoyl peroxide; t -Butylperoxyoctate, t-butylperoxyisobutyrate, t-butylperoxylaurate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butylperoxyisopropyl carbonate, 2 , 5-Dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, t-butylperoxybenzoate, di-t
One or more kinds of peroxyesters such as -butylperoxyisophthalate.

The amount of the radical polymerization initiator to be added is preferably 0 to 100 parts by weight of the raw material polypropylene-based resin because the sheet made of the modified polypropylene-based resin has good thermoformability and is economical. It is preferably in the range of 0.1 to 10 parts by weight, more preferably in the range of 0.2 to 5 parts by weight. Further, if necessary, the raw material polypropylene-based resin may contain an antioxidant, a metal deactivator, a phosphorus-based processing stabilizer, an ultraviolet absorber, an ultraviolet stabilizer, an optical brightener, a metal soap, an antacid adsorbent, etc. Stabilizers,
Alternatively, additives such as a crosslinking agent, a chain transfer agent, a nucleating agent, a lubricant, a plasticizer, a filler, a reinforcing material, a pigment, a dye, a flame retardant, and an antistatic agent are added as long as the effects of the present invention are not impaired. You may.

By having a nucleating agent present in the modified polypropylene resin, the thermoformability is not impaired.
The transparency of the polypropylene resin sheet can be improved. Examples of the nucleating agent include sodium benzoate, bisbenzylidene sorbitol, bis (p-
Methylbenzylidene) sorbitol, bis (p-ethylbenzylidene) sorbitol, sodium 2,2-methylenebis (4,6-di-t-butylphenyl) phosphite, and the like.

The amount of the nucleating agent to be added is such that the transparency of the polypropylene-based resin sheet is sufficiently improved and the economy is economical.
It is preferably 0.01 to 2 parts by weight based on parts by weight. Further, by the presence of an inorganic filler in the modified polypropylene resin, without impairing thermoformability, rigidity, surface properties of the polypropylene resin sheet,
Paintability, printability, etc. can be improved.

Examples of the inorganic filler include calcium carbonate, talc, glass fiber, magnesium carbonate, mica, kaolin, calcium sulfate, barium sulfate, titanium white, white carbon, carbon black, aluminum hydroxide, magnesium hydroxide and the like. One or more kinds may be mentioned. Of these, calcium carbonate and talc are preferred because they are easily available.
The average particle diameter of the inorganic filler is preferably about 10 μm or less, especially about 5 μm or less, from the viewpoint of improving the surface properties of the obtained polypropylene resin sheet.

The amount of the inorganic filler to be added is such that the rigidity of the polypropylene resin sheet is sufficiently improved and the surface property is not impaired.
It is preferably from 1 to 100 parts by weight, more preferably from 5 to 50 parts by weight, per 100 parts by weight. These raw materials polypropylene-based resin, isoprene monomer,
The order and method of mixing and melt-kneading of the radical polymerization initiator and other materials to be added are not particularly limited. For example, a raw material polypropylene-based resin, isoprene monomer, a radical polymerization initiator and, if necessary, May be melt-kneaded after mixing other additives, or the raw material polypropylene-based resin, radical polymerization initiator, and if necessary, other additives added and melt-kneaded, then the isoprene monomer is added. It may be melt-kneaded, or after obtaining the modified polypropylene resin by the above method, may be melt-kneaded with an additive or other resin added as necessary, or further a part of the raw material polypropylene. After reforming to form a masterbatch, it may be melt-kneaded with the remaining raw material polypropylene resin.

The heating temperature at the time of melt-kneading varies depending on the type of the resin and the like, but it is usually from 130 to 400 ° C. that the raw polypropylene resin is sufficiently melted, does not thermally decompose, and is sufficiently thermoformed. It is preferable in that the property can be obtained. The time for melt-kneading (the time after mixing the radical polymerization initiator and the isoprene monomer) is generally 30 seconds to 60 minutes.

Examples of the melt kneading apparatus include kneaders such as a co-kneader, a Banbury mixer, a Brabender, a single-screw extruder, a twin-screw extruder, a twin-screw surface renewer, and a twin-screw multi-disc apparatus. There is a device such as a horizontal stirrer or a vertical stirrer such as a double helical ribbon stirrer which can heat a polymer material to an appropriate temperature and knead it while giving an appropriate shear stress. Among these, a single-screw or twin-screw extruder is particularly preferred in terms of productivity.

The method for producing a sheet from the above-mentioned modified polypropylene resin is not particularly limited.
T-die extrusion molding, inflation molding, press molding, etc.
Die extrusion is preferred in terms of productivity. Further, the production of the modified polypropylene-based resin and the production of the sheet may be performed consistently, or the modified polypropylene-based resin may be produced, for example, pelletized, and then the sheet may be produced.

The modified polypropylene resin sheet provided in the present invention has a thickness of 0.1 to 5 mm, preferably 1 to 5 mm.
Since it is 3 mm and draw-down is small even when heated as well as used as a sheet, it can be suitably used for forming processes such as vacuum forming and pressure forming. Of the sheet comprising the modified polypropylene resin,
The drawdown at the time of heating, for example, after kneading the modified polypropylene resin with a roll at 200 ° C., press-molding at 200 ° C. to obtain a 1.5 mm thick sheet, and the sheet is reduced to 10 cm × 10 cm The sheet can be cut out, fastened with a frame having a 7.6 cm square opening, placed in an oven set at 190 ° C., and evaluated by measuring the amount of sag at the center of the sheet after 30 minutes.

The drawdown measured by the above method is at least about 70 mm for a commercially available polypropylene-based resin sheet, but according to the present invention, the drawdown can be completely reduced by selecting the conditions for modifying the starting polypropylene-based resin. It is also possible to obtain sheets that do not.

[0030]

Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples. Production of Modified Polypropylene Resin Ethylene propylene random copolymer (ethylene content 3% by weight, melt flow index at 230 ° C.
5 g / 10 min) 100 parts by weight and 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane 0.5 part by weight were stirred and mixed with a ribbon blender, and the mixture was mixed with a measuring feeder. It was supplied to a twin screw extruder (TEX44XCT-38) manufactured by Nippon Steel Works, and 1.5 parts by weight of an isoprene monomer was supplied from the middle of the extruder using a liquid addition pump. By melt-kneading and melt-extruding to obtain a modified polypropylene resin, PP1
The pellet was obtained.

The twin-screw extruder was of the same-direction twin-screw type, had a screw diameter of 44 mmφ, and had a maximum effective screw length (L / D) of 38. The set temperature of the cylinder portion of this twin-screw extruder was 180 ° C. until the isoprene monomer was injected, and 200 ° C. after the isoprene injection, and the screw rotation speed was set to 150 rpm. Table 1
Except that the types and amounts of the polypropylene resin, isoprene monomer and radical polymerization initiator described in
Similarly to P1, modified polypropylene resin, PP2
And PP3.

[0032]

[Table 1]

(Embodiment 1) The PP1 was set at a set temperature of 20.
The mixture was kneaded for 2 minutes with two rolls set at 0 ° C. and a rotation speed of 15 rpm, and the obtained roll sheet was press-formed at 200 ° C. to form a 1.5 mm thick sheet.
In the sag test, the sheet was cut into a size of 10 cm × 10 cm, and was stopped by a frame having an opening of 7.6 cm square. A metal object difference was attached to the leg portion of the frame for hanging measurement. The frame on which the sheet was stopped was placed in an oven set at 190 ° C., and the sag of the central part of the sheet after 30 minutes was measured. No sagging was observed. Comparative Example 1 A sheet was prepared by kneading a roll of an ethylene propylene random copolymer (ethylene content: 3% by weight, melt flow index at 230 ° C .: 0.5 g / 10 min) in the same manner as in Example 1 and press molding. When the sheet was manufactured and the sag of the sheet was measured, it was 76 mm. (Examples 2 and 3) A sheet was produced using PP2 or PP3 in the same manner as in Example 1, and the sag of the sheet was measured. Table 2 shows the composition of the sheet molding, and Table 3 shows the obtained results. (Example 4) The modified polypropylene resin of Example 1
A sheet was prepared by adding 0.5 parts by weight of bis (p-methylbenzylidene) sorbitol as a nucleating agent, and the sheet was sagged, and the total light transmittance and HAZE of the sheet were measured according to ASTM-D-1003. did. Table 3 shows the obtained results. Comparative Example 2 Bis (p) was used as a nucleating agent in an ethylene propylene random copolymer (ethylene content: 3% by weight, melt flow index at 230 ° C .: 0.5 g / 10 minutes).
(Methylbenzylidene) sorbitol was added in an amount of 0.5 part by weight to prepare a sheet. The sheet was sagged, and the total light transmittance and HAZE were measured. Table 3 shows the obtained results. Example 5 Example 3 A sheet was prepared by adding 50 parts by weight of calcium carbonate having a particle size of 1.6 μm as an inorganic filler to a modified polypropylene resin, and the sag of the sheet was measured. Further, the polypropylene-based sheet is
A sheet having a thickness of 3.2 mm was prepared by stacking and pressing at 200 ° C., and the flexural modulus was measured according to ASTM-D-790. Table 3 shows the obtained results. (Comparative Example 3) Calcium carbonate having a particle diameter of 1.6 µm was added to a propylene homopolymer (melt flow index at 230 ° C, 0.5 g / 10 min) as an inorganic filler.
A sheet was prepared by adding parts by weight, and the sag and flexural modulus of the sheet were measured in the same manner as in Example 5. Table 3 shows the obtained results.

[0034]

[Table 2]

[0035]

[Table 3]

The sheet made of the modified polypropylene resin in the examples has a small drawdown even when heated in an oven at 190 ° C. and is excellent in thermoformability, whereas the unmodified ethylene resin shown in Comparative Example 1 It can be seen that the sheet made of the propylene random copolymer has a large drawdown and is inferior in thermoformability. Further, the sheet to which the nucleating agent of Example 4 was added had a small HAZE as well as a drawdown, indicating that the sheet was excellent in thermoformability and transparency. Furthermore, since the sheet to which the inorganic filler of Example 5 was added has a small drawdown and a high flexural modulus, it can be understood that the sheet is excellent in thermoformability and rigidity.

[0037]

The sheet made of the modified polypropylene resin of the present invention hardly causes drawdown during melting,
It can be suitably used for molding such as vacuum molding and compressed air molding, and when these molding methods are used, molding conditions can be selected from a wide range of conditions.

The presence of a nucleating agent in the modified polypropylene resin improves the transparency, the presence of an inorganic filler improves the rigidity, and improves the drawdown resistance while maintaining the drawdown resistance. be able to.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 7:00 C08L 23:04

Claims (2)

[Claims] 1. A sheet comprising a modified polypropylene resin obtained by melt-kneading a polypropylene resin, an isoprene monomer and a radical polymerization initiator. 2. A molded product obtained by vacuum forming or pressure forming the sheet according to claim 1.