JPS624066B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to glass fiber reinforced polyolefins with improved mechanical properties. More specifically, for that purpose, the present invention includes blends of polyolefins and glass fibers containing additives or binders capable of promoting adhesion of the fibers to the polymer during processing steps. It is known that polyolefins are not suitable for effective reinforcement with inorganic fibers due to their non-polar nature. In order to overcome such deficiencies, it has been suggested to modify olefin polymers by grafting them onto hydrocarbon chain monomers having polar groups. Olefin polymers to be reinforced with inorganic fibers by techniques that generally foresee polar monomers and a preliminary chemical treatment of the polymer with ionizing radiation or agents capable of forming active centers on the polymer chain, such as peroxides. Examples of modifying coalescence are known. and supplying the converter with a mixture of olefin polymer, glass fiber, polar monomer and peroxide;
It is then also possible to carry out the grafting reaction directly in the converter by bringing the mass to the forming temperature. Moreover, in addition to the formation of toxic volatile products, complete decomposition of the peroxide is generally difficult in this case, and its residues are therefore particularly detrimental to the long-term properties of the composite material. Defects occur due to the influence of Furthermore, treating polyethylene or polypropylene with peroxides in the molten state causes changes in the melt index of the polymer that are difficult to control and reproduce. This time, unexpectedly, crystalline polyolefins (especially polyethylene, polypropylene, polybutene and poly-4-methylpentene-1), glass fibers and general formula: [In the formula, X is a (CHR)n group (n is an integer from 2 to 18, and R is hydrogen or an alkyl group having 1 to 6 carbon atoms), or X has multiple nuclei is an optional alicyclic or aromatic divalent group, or a heterocyclic group; when R′ is hydrogen and X is a (CHR)n group, the two R′ together It has now been found that starting from mixtures of bis-maleamic acids of the form (CHR)n groups can be obtained, composite materials with excellent mechanical properties can be obtained, which form the subject of the present invention. Representative and preferred bis-mareamic acids are N,N'-hexamethylene-bis-mareamic acid; N,N'-ethylene-bis-mareamic acid; N,N'-trimethylene-bis-mareamic acid; N'-dodecamethylene-bis-maleamic acid; N,N'-piprazine-bis-maleamic acid; N,N'-m-phenylene-bis-maleamic acid; N,N'-3,3'-(trans- Stilbene
N,N-4,4'-(diphenyl ether)-bis-maleamic acid; N,N'-4,4'-(diphenylmethane)-bis −
Maleamic acid; N,N'-isophorone-bis-maleamic acid
^* ; N,N'-2,5-dimethylene-norbornane-bis-maleamic acid *See footnote to Table 2. The composite material is produced by heating a blend of polyolefin, glass fibers and bis-maleamic acid without requiring the use of peroxides or other substances capable of supplying free radicals. Bis-maleamic acid is related to polyolefins.
Amounts are used which can vary from 0.5% to 5% by weight. The term crystalline polyolefin also includes crystalline copolymers of alpha-olefins with each other or with ethylene. More specifically, the term includes products containing up to about 20% by weight of polymerized ethylene obtained by polymerizing propylene in the presence of ethylene added at the beginning of or during the polymerization of propylene. As mentioned above, the process for making the composite material of the present invention involves producing a mixture of polymer, glass fiber and bis-maleamic acid and then subjecting the resulting "dry blend" to a temperature generally equal to 200°C and the decomposition temperature of the polymer. In fact, it consists in heating at a temperature that corresponds to the forming temperature of the polymer. In the case of polypropylene, the molding temperature is 200-290
Included between ℃. In practice, the production of the composite material of the invention or the production of a corresponding product consists of a mixture containing a polymer, glass fibers and bis-maleamic acid, or a granular material obtained by granulation from said mixture by known methods. This is done by molding using known techniques. Fibers generally constitute 10-50% by weight of the polyolefin/fiber blend. The glass fibers used are those which have been previously treated with silane and a film-forming agent which has a surface tension close to that of the polyolefin matrix in the molten state. Examples of such silanes include γ-aminopropyl-triethoxysilane, aminoethyl-triethoxysilane, γ-aminobutyl-triethoxysilane and γ-glycidoxy-propyltrimethoxysilane. The above-mentioned film forming agent is a polyolefinic material, and for example, polypropylene, polyethylene, ethylene-propylene rubber, and ethylene-propylene-diene rubber may be used. Such olefin rubber is 50000~800000,
Preferably has a molecular weight of 70,000 to 500,000, 20 to 80 mol% of ethylene, and when unsaturated, butadiene, isoprene, 1,3-pentadiene, 1,
4-pentadiene, 1,4-hexadiene, 1,
5-hexadiene, 1,9-decadiene, 5-methylene-2-norbornene and 5-vinyl-2-
Conjugated or non-conjugated diene hydrocarbons such as alkenyl-norbornene such as norbornene, norbornadiene such as 2-alkyl-2,5-norbornadiene, alkylidene-norbornene such as 5-ethylidene-2-norbornene, cyclopentadiene, etc. Contains 20 mol%. The glass fibers are treated with silanes and film formers by any of the known coating techniques. As mentioned above, the blends of the present invention provide excellent polymer adhesion to the fibers, thus achieving significantly higher failure loads than would be achieved without the use of bis-maleamic acid, and preventive polymerization. This can be accomplished without the need for modification or reversion to the use of peroxides. In addition to avoiding expensive processes for preventive modification of polymers, this method also avoids problems associated with the use of free radical sources, such as cross-linking, quality loss and poor resistance to aging of the product. All defects are also avoided. Crystalline polypropylene, polybutene, poly4
- As methylpentene-1, it is preferable to use a polymer having a high proportion of isotactic structure polymer. More preferably, polypropylene having an isotacticity index of greater than 90% is used. In the following example, given merely by way of illustration and not by way of limitation, the glass fibers used therein were γ
-aminopropyl-triethoxysilane with 67% ethylene, 30% propylene and 5-ethylidene-2
- with a coating based on a terpolymer consisting of 3% of norbornene (the percentages are indicated by weight). Examples 1 to 4 1400 g of polypropylene in powder form having an isotacticity index of 95, a density of 0.90 g/cc and a melt index L = 10 g/10 min (ASTM-1238) were mixed with N, N'-
Hexamethylene-bis-maleamic acid and antioxidant formulation in a powder mixer under a nitrogen atmosphere for 5 minutes.
Mixed for a minute. This antioxidant formulation consists of 0.2% dilaurylthiodipropionate, pentaerythritol tetra[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]
0.1%, Ca stearate 0.2% and 2,6-di-t
-butyl-p-cresol 0.1% (% by weight relative to polypropylene). For comparison, four tests did not initially use bis-maleamic acid. 4 "dry blend" was extruded in a Pasquetti twin screw extruder at 205° C. under a nitrogen atmosphere, thereby obtaining a modified and stabilized granular polypropylene. This granular product has a tipped strand shape with a length of 6 mm.
30% (based on the total) of glass fibers were added and the entire mass was then extruded at 205° C. in a Pasketch twin screw extruder, thereby obtaining reinforced polypropylene. Bresso specimens for physical and mechanical properties
The extruder was manufactured using a V160/72 injection molding machine manufactured by GBF (Italy) operating under the following conditions: - extruder body and head temperature 250°C - die temperature 25°C - tensile test specimens Injection time 20 seconds - complete cycle for tensile test specimens 70 seconds - for bending, impact and HDT specimens Injection time 80 seconds - for bending, impact and HDT specimens Complete cycle 100 seconds in 4 tests Tensile failure load (ASTM D-638), flexural modulus (ASTM
D-790), Notched Izot Resilience at -20℃ (ASTM D-256), HDT (Heat Strain Temperature) (ASTM D-648), and Center of Tensile Test Specimen (Distance Between Supports) 4cm) 80℃ and
Table 1 shows the creep values in a bending test conducted at 120° C. for 8 hours under a load of 100 kg/cm ² .

[Table] Examples 5 to 8 Isotacticity index 95, density 0.90g/cc and melt index L = 10g/10min (ASTM
1400 g of polypropylene powder having the following properties (D-1238) were added in a powder mixer under a nitrogen atmosphere to 600 g of chopped strand type glass fibers of 6 mm length and bis-maleamic acid in the amounts shown in Table 2 and Examples 1 to 4.
and the same antioxidant formulation used for 5 minutes. The resulting 4 "dry blend" was injection molded as in Examples 1-4 and its properties determined. The results are shown in Table 2.

[Table] Example 9 Density 0.962g/cc and melt index E=
1,400 g of high-density polyethylene powder with 5.5 g/10 min (ASTM D-1238) was mixed with 600 g of chopped strand type glass fiber of 6 mm length in a powder mixer in a nitrogen atmosphere, and N,N'-hexamethylene-bis-maleamic acid. 7g and n-octadecyl 3-(4-hydroxy-3,5-di-t-butylphenyl)propionate 0.03%, 2,6-di-t-butyl-p-cresol 0.02%, glyceryl monostearate 0.04% and Ca stearart
Mix for 5 minutes with an antioxidant formulation containing 0.1% (% on polyethylene). The resulting dry blends were injection molded and characterized as in Examples 1-4. Tensile breaking load (ASTM D-638) is 950Kg/cm ²
The flexural modulus (ASTM D-790) is 63650.
It was Kg/ ^cm2 . Notched Izots resilience (ASTM D-256) at -20℃ is 30Kg cm/cm (partial destruction of test piece), HDT (ASTM D-648) is
It was 123℃.

Claims (1)

[Scope of Claims] 1. A blend comprising (a) 50 to 90% by weight of crystalline polyolefin and (b) 50 to 10% by weight of glass fiber, wherein the blend has the general formula: [In the formula, X is a (CHR)n group (n is an integer from 2 to 18, and R is hydrogen or an alkyl group having 1 to 6 carbon atoms), or X has multiple nuclei is an optional alicyclic or aromatic divalent group, or a heterocyclic group; when R′ is hydrogen and X is a (CHR) _o group, the two R′ together A blend characterized in that it contains 0.5 to 5% by weight of bis-maleamic acid represented by (CHR) _o group-forming with respect to the polyolefin. 2. The blend according to claim 1, which contains N,N'-hexamethylene-bis-maleamic acid as the bis-maleamic acid. 3. A blend according to claim 1, which contains N,N'-dodecamethylene-bis-maleamic acid as the bis-maleamic acid. 4. The blend according to claim 1, which contains N,N'-isophorone-bis-maleamic acid as the bis-maleamic acid. 5. The blend according to any one of claims 1 to 4, wherein the crystalline polyolefin is polypropylene. 6. The blend according to any one of claims 1 to 4, wherein the crystalline polyolefin is polyethylene.