JPH04351648A - Polypropylene resin composition and molded foam prepared therefrom - Google Patents

Abstract

PURPOSE:To provide a polypropylene resin composition which has excellent expansion stability and good heat resistance and can prevent expansion moldability from decreasing even when a filler for improving heat resistance is added. CONSTITUTION:A polypropylene resin composition comprising 100 pts.wt. polypropylene polymer and 0.1-10 pts.wt. modified olefin polymer, and a molded foam prepared from the composition.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a polypropylene resin composition and a foam molded article made from the composition, and more particularly to a resin composition that stably and easily provides a foam molded article and a foam molded article made from the same. Regarding.

0002

BACKGROUND OF THE INVENTION Polypropylene is a useful polymeric material that is used in a wide variety of fields because it is inexpensive and has excellent heat resistance. However, polypropylene has a high degree of crystallinity and is characterized by a rapid change in melt viscosity around the crystalline melting point, which makes foam molding difficult.

Various attempts have been made to solve these problems. For example, in JP-A-50-75662, an attempt has been made to reduce the temperature dependence of the melt viscosity by mixing polyethylene or the like with a low degree of crystallinity and a smaller temperature dependence of the melt viscosity. However, this method has the problem that unless a large amount of polyethylene, such as 10% or more, is mixed with polypropylene, it is not effective in improving the foam moldability of polypropylene, and as a result, the heat resistance, which is a characteristic of polypropylene, is significantly reduced.

In addition, the viscosity adjustment method by crosslinking disclosed in Japanese Patent Publication No. 46-31754 generally does not allow continuous foaming and requires two steps of crosslinking and heat foam molding, resulting in low productivity. There is also the problem that the resulting foam cannot be recycled because it undergoes a crosslinking reaction.

Further, JP-A-1-278539 discloses a method of mixing an amorphous resin such as polystyrene in order to suppress the temperature dependence of the melt viscosity of polypropylene. Although this method is effective in adjusting the melt viscosity, the polypropylene and amorphous resin are incompatible, so phase separation occurs locally in the foam, resulting in the problem that only foams with non-uniform cells can be obtained. There is.

Conventionally, fillers have been added for the purpose of improving heat resistance, but as the amount of fillers increases, the temperature dependence of viscosity increases, resulting in poor foaming stability.

[0007]

[Problems to be Solved by the Invention] Despite the market's high expectations for polypropylene foams, at present no fully satisfactory polypropylene foam molded product has been commercialized. An object of the present invention is to provide a polypropylene resin composition and a foamed molded product thereof that fully meets these expectations.

[0008]

[Means for Solving the Problems] In view of the above circumstances, the present inventors have conducted intensive research to solve the above problems. By mixing a specific modified olefin polymer with a polypropylene polymer, the crystallization temperature The temperature dependence of the melt viscosity in the vicinity is reduced, making stable foam molding possible, and the amount of modified olefin polymer used in the basic polypropylene resin is so small that it does not reduce the heat resistance of the polypropylene resin. The present invention has been completed based on the discovery that foam molding can be carried out stably despite the presence of heat resistance, and that deterioration in foam moldability due to fillers added to improve heat resistance can be suppressed.

That is, the first aspect of the present invention is to combine 100 parts by weight of a polypropylene polymer and 0.1 parts by weight of a modified olefin polymer.
The second aspect of the present invention is a polypropylene resin composition comprising 10 parts by weight of the above resin composition.

The modified olefin polymer used in the present invention is a modified olefin polymer having a branched structure. The modified olefin polymer having a branched structure is a compound having a reactive group capable of polymerizing with olefins, such as a vinyl group, and at least one amide group and one or both of a glycidyl group and a glycidyloxy group. It may be produced by copolymerization of a compound containing an olefin with an olefin, or it may be a compound having a reactive group capable of polymerizing with the above-mentioned olefin, such as a vinyl group, in the polyolefin chain after producing a polyolefin by a normal polymerization method. ,
In addition, a compound having at least one amide group and at least one glycidyl group or glycidyloxy group or both may be introduced by graft polymerization using a conventional method.

The present invention will be explained by showing an example of such a modified olefin polymer. For example, the modified olefin polymer is obtained by copolymerizing a compound represented by the following general formula (II) and an olefin polymer, and the following general formula (I) is used per 2 to 1000 repeating units of the olefin.

0012

[Case 2]

A structural unit having a glycidyl group represented by (wherein, Ar represents a C6-C23 aromatic hydrocarbon group having at least one glycidyloxy group, and R represents a hydrogen atom or a methyl group) Examples include modified olefin polymers having one.

The compounds represented by the general formula (II) are as follows.

[0015]

[Chemical formula 3]

(In the formula, Ar represents a C6-C23 aromatic hydrocarbon group having at least one glycidyloxy group, and R represents a hydrogen atom or a methyl group.)

0017
] The compound represented by the general formula (II) is disclosed in JP-A-60-1
It can be manufactured by a method such as that described in No. 30580. That is, the following general formula (III)

[0018]

[C4]

After adding epihalohydrin to the compound represented by (wherein, Ar' represents a C6-C23 aromatic hydrocarbon having at least one hydroxyl group, and R is a hydrogen atom or a methyl group), , can be produced by performing a dehydrohalogenation reaction with an alkali.

For example, when 2,6-xylenol N-methylolacrylamide is used as the starting material,
Structural formula (IV) below

[0021]

[C5]

A compound represented by the following formula can be obtained.

The modified olefin polymer of the present invention can be obtained by copolymerizing the compound of the above general formula (II) with the olefin polymer shown below. Examples of olefin polymers used in the present invention include ethylene, propylene,
A homopolymer of 1-butene, 1-pentene, isobutene, etc., or a random copolymer, block copolymer, or graft copolymer thereof, which may be used alone or in combination of two or more.

The above olefin polymer and general formula (II)
There are no particular restrictions on the method for producing a copolymer with the compound, but the following two methods can be suitably used. The first production method is a graft modification method of an olefin polymer, and the second production method is a method of graft modification of an olefin polymer, and a second production method is a method of graft modification of an olefin polymer.
This is a method of copolymerizing a compound having a glycidyl group as shown in II). The first production method, which is a graft modification method of an olefin polymer, combines two components (A) an olefin polymer and (B) a compound represented by the above general formula (II) with (C) a radical Radical addition is performed using a polymerization initiator. At this time, a solvent that dissolves or swells the olefin polymer, such as tetralin, decalin, toluene, xylene, or chlorobenzene, may be used. Alternatively, the reaction may be carried out in a molten state using a melt kneading device such as an extruder, kneader, or heating roll without using a solvent. There are no particular restrictions on the radical polymerization initiator, and commonly used radical polymerization initiators can be used. For example, peroxides such as cumene hydroperoxide, tert-butyl hydroperoxide, benzoyl peroxide, lauroyl peroxide, decanoyl peroxide, acetyl peroxide, or azo compounds such as azobisisobutyronitrile are used alone or in combination of two or more. It will be done.

Olefin monomer and the above general formula (II)
The second production method, which is a method of copolymerizing a compound represented by the following, is a method of copolymerizing an olefin monomer and a compound represented by the above general formula (II). There are no particular restrictions on the copolymerization method, and in addition to general radical polymerization, cationic polymerization, and anionic polymerization, coordination polymerization using a transition metal can also be used.

General formula (II) to the above olefin polymer
) Modified olefin polymers produced by radical addition of compounds represented by formula (2) or copolymerization of olefin monomers and compounds of general formula (II) are random copolymerizations of olefin polymers and compounds of general formula (II). It may be a polymer, a graft copolymer, a block copolymer, etc., but
In any polymer, the following general formula (I) is used per 2 to 1000 repeating units of olefin.

002
7]

[C6]

A structural unit having a glycidyl group represented by (wherein, Ar represents a C6-C23 aromatic hydrocarbon group having at least one glycidyloxy group, and R represents a hydrogen atom or a methyl group) It is necessary to have one. If the grafting ratio exceeds 1000 repeating units of the polymer, the modification of the olefin polymer is insufficient, and the temperature dependence of the melt viscosity near the crystallization temperature when mixed with the polypropylene polymer is reduced. effect is not fully demonstrated.

The polypropylene polymer used in the present invention may contain 5 to 30 parts by weight of other polymers such as polyethylene, polybutene, polybutadiene, etc. Further, copolymers of propylene and other monomers such as propylene-ethylene copolymers, propylene-butene copolymers, propylene-acrylic acid esters, etc. may also be used.

The resin composition of the present invention is blended in an amount of 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, per 100 parts by weight of the polypropylene polymer. If the amount of the modified olefin polymer is less than 0.1 parts by weight, the effect of reducing the temperature dependence of melt viscosity will not be sufficient, and if it exceeds 10 parts by weight, heat resistance will decrease and costs will increase. Moreover, talc, mica, calcium carbonate, etc. can also be added as fillers to improve heat resistance. It is also possible to directly blend these fillers, but if the blending amount is 5 parts by weight or more per 100 parts by weight of the polypropylene polymer, prepare a mixture of polypropylene and filler in advance and use the resulting masterbatch. A method of foam molding is preferred because the filler can be uniformly dispersed in the polypropylene.

The mixing method and foam molding method for the polypropylene polymer and the modified olefin polymer may be any conventional method and are not particularly limited. The blending method, the method of mixing the two in advance and extrusion molding into pellets (so-called masterbatch) with the polypropylene polymer, and the foam molding method include the extrusion foaming method, pressure foaming method, and normal pressure foaming method. Foaming, injection foaming, in-mold foaming, etc. can be used. For example, 0.1 to 1 part of the above modified olefin polymer is added to 100 parts by weight of polypropylene resin.
A foamed seed having a foaming ratio of 2 to 10 times and a thickness of 1 to 5 mm is obtained by mixing a resin containing 0 parts by weight (preferably 1 to 5 parts by weight) with a foaming agent under high temperature and high pressure, and extruding it into a low pressure zone. be able to. In addition, polypropylene resin 1
00 parts by weight, 0.1 to 10 parts by weight (preferably 1 to 5 parts by weight) of a modified olefin polymer, and 1 to 50 parts by weight (preferably 10 to 30 parts by weight) of a filler to improve the heat resistance of the resin.
By mixing a resin containing (parts by weight) with a foaming agent under high temperature and high pressure and extruding it into a low pressure zone, a foaming ratio of 2 to 10 times,
It is also possible to obtain a foamed sheet with a thickness of 1 to 5 mm.

[0032]

[Effects of the Invention] By blending the modified olefin polymer with the polypropylene polymer, the resin composition of the present invention reduces the temperature dependence of the melt viscosity near the crystallization temperature, making stable foam molding possible. . Furthermore, although the amount of modified olefin polymer used relative to the basic polypropylene resin is so small that it does not reduce the heat resistance of the polypropylene resin, it not only enables stable foam molding but also improves heat resistance. It is possible to suppress deterioration in foam moldability due to fillers added for this reason.

[0033]

EXAMPLES The present invention will be explained in more detail below based on Examples, but the present invention is not limited to these.

Reference example: Production of modified olefin polymer Commercially available polypropylene (manufactured by Union Polymer Co., Ltd., A
H561) 100 parts by weight, 100 parts by weight of the modifier represented by the above structural formula (IV), and α,α'-(t-butylperoxy-m-isopropyl)benzene (manufactured by NOF Corporation, Perbutyl P) 0 .1 part by weight was dry blended using a 44 mm co-directional twin screw extruder (manufactured by Japan Steel Works, TE).
X44) at a rate of 9 kg/hour. The extruder temperature was set at 210°C. The extrudate was cooled with water, pelletized, and then dried under reduced pressure at 70° C. for 12 hours. After pulverizing the obtained dry pellets and washing them five times with acetone to remove unreacted modifier and modifier homopolymer, the infrared absorption spectrum and elemental analysis values of nitrogen atoms contained in the resin were determined. The amount of grafting of the modifier is 37.1
%Met. The obtained modified olefin polymer had one structural unit having a glycidyl group represented by the general formula (1) for every 49 repeating units of the olefin.

Example 1 Polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen D
-501, melt index: 0.4g/10min) 1
00 parts by weight, 3 parts by weight of the modified olefin polymer produced in the reference example, and 0.1 parts by weight of dicumyl peroxide were powder blended in a blender, gelled in a 40-50φ tandem extruder, and pressed into 3 parts by weight of butane. After mixing with the resin, the mixture was cooled to a resin temperature of 160°C and extruded through a circular die (diameter: 75φ, clearance: 0.3mm) to obtain a foamed sheet with a thickness of 1.5mm and a width of 64mm.

Example 2 Polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen D
-501, melt index: 0.4g/10min) 1
00 parts by weight, 100 parts by weight of Calpet (manufactured by Hayashi Kasei Co., Ltd., a mixture of 60% calcium carbonate and 40% polypropylene), 4.2 parts by weight of the modified olefin polymer produced in the reference example, and 0.14 parts by weight of dicumyl peroxide. The weight part was powder blended in a blender, gelled in a 40-50φ tandem extruder, mixed with 3 parts by weight of butane by press injection, cooled to a resin temperature of 160°C, and passed through a circular die (diameter: 75φ, clearance: 0.3mm). more extruded,
A foamed sheet with a thickness of 1.5 mm and a width of 64 mm was obtained.

Comparative Example 1 Polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen D
-501, melt index: 0.4 g/10 minutes) was gelled in a 40-50φ tandem extruder, mixed with 3 parts by weight of butane by press-fitting, cooled to a resin temperature of 160℃, and passed through a circular die (diameter: 75φ, clearance :
extruded from 0.3mm), thickness 1.5mm, width 64mm
A foamed sheet was obtained.

Comparative Example 2 Polypropylene resin (manufactured by Sumitomo Chemical Co., Ltd., Sumitomo Noblen D
-501, melt index: 0.4g/10min) 1
00 parts by weight, 100 parts by weight of Calpet (manufactured by Hayashi Kasei Co., Ltd., a mixture of 60% calcium carbonate and 40% polypropylene) was powder-blended in a blender, gelled in a 40-50φ tandem extruder, and then press-fitted with 3 parts by weight of butane. After mixing, the resin was cooled to a temperature of 160°C and extruded through a circular die (diameter: 75φ, clearance: 0.3mm) to obtain a foamed sheet with a thickness of 1.5mm and a width of 64mm.

The foamed sheets obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were measured for expansion ratio and closed cell ratio. The results are shown in Table 1. The closed cell ratio is an index indicating the stability of foaming, and was measured according to ASTM D-2856. The foaming ratio is determined by the density ρ0 (g/cm3) of the raw material resin.
) and the density ρ (g/cm3) of the foamed molded body, ρ0
/ρ.

[0040]

[Table 1]

Example 1 and Comparative Example 1 or Example 2 in Table 1
From Comparative Example 2, it can be seen that by blending the modified olefin polymer, the closed cell ratio increased and stable foam molding was achieved. Furthermore, from Examples 1 and 2, when the instability of foam molding caused by the inclusion of calcium carbonate as a filler was evaluated by the decrease in closed cell ratio, when the modified olefin polymer of the present invention was included. is 80% to 7
It only decreases to 0%. On the other hand, when no modifier is included, the reduction in closed cell ratio due to the inclusion of calcium carbonate is 30 to 15% from Comparative Examples 1 and 2.
The rate of decrease is large. Thus, it can be seen that by using the resin composition of the present invention, high foam molding stability can be maintained even when it contains calcium carbonate as a filler.

Claims (6)

[Claims] 1. A polypropylene resin composition comprising 100 parts by weight of a polypropylene polymer and 0.1 to 10 parts by weight of a modified olefin polymer. 2. A modified olefin polymer having one structural unit having at least one amide group and at least one glycidyloxy group or glycidyl group per 2 to 1000 repeating units of olefin. The composition according to claim 1, which is a polymer. 3. The modified olefin polymer has the following general formula (I) for every 2 to 1000 repeating units of olefin: (wherein, Ar has at least one glycidyloxy group) 3. The composition according to claim 2, which is a modified olefin polymer having one structural unit having a glycidyl group represented by C23 aromatic hydrocarbon group, R represents a hydrogen atom or a methyl group. [Claim 4] The amount of modified olefin polymer is 1 to 5.
A composition according to claim 1, in parts by weight. 5. The composition according to claim 1, further comprising 1 to 50 parts by weight of a filler. 6. A polypropylene foam molded article comprising the resin composition according to claims 1 to 5.