JPS6223656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a laminate comprising a polypropylene resin and a metal.

It is a laminate of synthetic resin and metal, and is widely used by taking advantage of the characteristics of each. For example, by coating the surface of a metal molded article with a synthetic resin thin film, corrosion and rusting of the metal can be prevented. In addition, the metal sandwich panel, which has a synthetic resin sheet between two metal thin films, has a metal surface, is light as a synthetic resin, and has far superior mechanical properties than molded products made of synthetic resin alone. It has heat resistance and heat resistance, making it possible to reduce weight and cost by using it as, for example, automobile parts. Polypropylene has the lowest specific gravity among synthetic resins, has excellent mechanical properties such as rigidity and heat resistance, and is inexpensive.Therefore, there has been a strong demand for lightweight and low-cost automobiles, and it has become popular in metal sandwich panels. Studies are underway as an intermediate layer resin. However, since polypropylene is nonpolar, it exhibits almost no adhesion to metals, and as it is, it is not possible to obtain a laminate that firmly adheres to metals. Conventionally, in order to improve adhesion, surface treatments such as corona discharge treatment, chromic acid treatment, flame treatment, and etching are applied to the surface of polypropylene and/or metal, and modified polyolefins, which are polyolefins grafted with maleic anhydride, have been used. methods (e.g., Japanese Patent Publication Nos. 10757/1982 and 4822), methods using compositions in which acid-modified polyolefin is blended with synthetic hydrocarbon elastomers and ethylene polymers (e.g., Japanese Patent Publication Nos. 80334/1983, 56-21850) are known. However, when the polypropylene/metal laminate produced by these methods reaches a temperature above the melting point of polypropylene,
It easily deforms due to its own weight or external force, resulting in a problem of poor high-temperature heat resistance.

It is generally well known that by crosslinking polymeric substances, melt deformation resistance and high temperature heat resistance are greatly improved. However, polypropylene is a thermally decomposable polymer, and when mixed with an organic peroxide and heated, crosslinking does not occur, but on the contrary, it decomposes and its viscosity decreases. Therefore, in order to thermally crosslink polypropylene, a method has been adopted in which a crosslinking aid such as divinylbenzene or liquid 1,2 polybutadiene is mixed with a radical generator and heated. However, the crosslinked polypropylene obtained in this way not only does not adhere to metal at all, but it is extremely difficult to form it into a film or sheet, for example, and it is almost impossible to use it to produce a laminate with metal. It's impossible.

The inventors of the present invention have conducted intensive studies on a method for producing a polypropylene/metal laminate with good high-temperature resistance, and have developed the present invention by using a specified organic peroxide on modified polypropylene and press-bonding it under specific conditions. I was able to complete it. That is, the present invention provides a composition comprising a modified polypropylene partially or entirely grafted with unsaturated carboxylic acids, a crosslinking aid, and an organic peroxide whose 1-minute half-life temperature is 10° C. or more higher than the melting point of the modified polypropylene. A polypropylene resin that presses an object and a metal at a temperature higher than the melting point of the modified polypropylene and lower than the one-minute half-life temperature of the organic peroxide, and then heated to a temperature equal to or higher than the one-minute half-life temperature of the organic peroxide. This is a method for manufacturing a laminate including a layer and a metal layer. According to the present invention, the polypropylene composition is formed into, for example, a film or a sheet (collectively referred to as a sheet-like material) at a temperature lower than the 1-minute half-life temperature of the organic peroxide, and then the metal and the organic Also provided is a method for producing a laminate in which the laminate is press-bonded at a temperature equal to or higher than the 1-minute half-life temperature of peroxide.

The modified polypropylene used in the present invention can be obtained by grafting unsaturated carboxylic acids onto polypropylene by any method. The content of graft unsaturated carboxylic acids in the modified polypropylene is generally preferably from 0.005 to 5% by weight. The content of graft unsaturated carboxylic acids is
If it is less than 0.005% by weight, the adhesive strength with metal will be weak, and if it exceeds 5% by weight, not only will the manufacturing cost increase, but the adhesive strength will reach saturation. Methods for producing modified polypropylene include, for example, a method of reacting in a molten state (for example, Japanese Patent Publication No. 43-27421);
A method of reacting in a solution state (for example,
15422), a method of reacting in a slurry state (for example, Japanese Patent Publication No. 18144-1977), and a method of reacting in a gas phase (for example, Japanese Patent Application Publication No. 77493-1987).
Among these methods, the melt-kneading method using an extruder is preferred because it is easy to operate.

The polypropylene used to produce modified polypropylene is not particularly limited, and includes homopolypropylene, propylene-ethylene block copolymer, propylene-ethylene random copolymer, copolymer of propylene and α-olefin,
and mixtures thereof are used. Among these, propylene-ethylene random copolymers and propylene-ethylene block copolymers are particularly preferably used. The melting point of these polypropylenes varies depending on the tacticity and comonomer content, but is generally in the range of 130 to 170°C.

Examples of unsaturated carboxylic acids used to produce modified polypropylene include acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, and their acid anhydrides, esters, amides, imides, Metal salts, such as maleic anhydride, citraconic anhydride, itaconic anhydride, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, butyl methacrylate, glycidyl acrylate, glycidyl methacrylate,
Maleic acid monoethyl ester, maleic acid diethyl ester, pumalic acid monomethyl ester, pumalic acid dimethyl ester, itaconic acid monomethyl ester, itaconic acid diethyl ester, acrylamide, methacrylamide, maleic acid monoamide, maleic acid diamide, maleic acid N-mono Ethylamide, maleic acid-N,N-diethylamide, maleic acid-N-monobutylamide, maleic acid-N,N-dibutylamide, fumaric acid monoamide, fumaric acid diamide, fumaric acid-N-monoethylamide, fumaric acid -N,N-diethylamide, fumaric acid-N-monobutylamide, fumaric acid-N,N-dibutylamide, maleimide, N-
Butylmaleimide, N-phenylmaleimide, sodium acrylate, sodium methacrylate,
Examples include potassium acrylate and potassium methacrylate. Among these, it is most preferable to use maleic anhydride.

Modified polypropylene includes various unmodified polypropylenes as mentioned above, polymeric substances other than polypropylene to the extent normally used, inorganic and organic fillers,
It may contain heat stabilizers, weather stabilizers, lubricants, antistatic agents, nucleating agents, pigments, dyes, flame retardants, antiblocking agents, and the like.

The crosslinking aid used in the present invention is a compound having two or more double bonds in one molecule, such as a compound with a number average molecular weight of 500, containing divinylbenzene, diallyl phthalate, triallyl glycerate, or diene monomer as the main component. ~10000 liquid rubber, e.g. 1,
2-polybutadiene, 1,4-polybutadiene,
Styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, or 1,2-polybutadiene having functional groups such as carboxyl group, hydroxyl group, mercapto group, halogen atom, amino group, aziridino group, and epoxy group in the molecule,
Examples include 1,4-polybutadiene, polyisoprene, polychloroprene, 1,2-polypentadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, butadiene-isoprene copolymer, butadiene-pentadiene copolymer, and divinylbenzene and liquid 1,2 -Polybutadiene is preferably used. The amount of crosslinking aid added is based on modified polypropylene.
The amount is 1 to 50 parts by weight per 100 parts by weight, preferably 3 to 30 parts by weight per 100 parts by weight of modified polypropylene. If the amount of the crosslinking aid added is less than 1 part by weight, the effect of improving high temperature heat resistance will be small, and if it exceeds 50 parts by weight, the rigidity at temperatures below the melting point of the modified polypropylene will be significantly lowered, which is undesirable.

In the present invention, as an organic peroxide, the 1-minute half-life temperature (temperature at which it decomposes by half in 1 minute) is the melting point of modified polypropylene (the peak temperature of the endothermic curve measured with a differential scanning calorimeter at a heating rate of 10°C/min). Than
It is necessary to use a temperature higher than 10℃. As mentioned above, the melting point of modified polypropylene is generally
Since the temperature is in the range of 130 to 170°C, an organic peroxide whose half-life temperature in 1 minute is generally 140°C or higher is used. Examples of such organic peroxides include 2,
4,4-trimethylpentyl-2-hydroperoxide, diisopropylbenzene hydroperoxide, cumene hydroperoxide,
t-Butyl hydroperoxide, dicumyl peroxide, 2,5-dimethyl-2,5-di-
(t-butylperoxy)-hexane, 1,3-bis-(t-butylperoxy-isopropyl)-benzene, t-butylcumyl peroxide, di-
t-Butyl peroxide, 2,5-dimethyl-
2,5-di-(t-butylperoxy)-hexyne-3.1,1-di-t-butylperoxy-3,
3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, 2,2
-di-(t-butylperoxy)-butane, 4,4
-di-t-butylperoxyvaleric acid-n-butyl ester, di-t-butylperoxy-hexahydroterephthalate, di-t-butylperoxyazelate, t-butylperoxy-3,5, 5-Tolumethylhexoate, t-
These include butyl peroxyacetate, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, succinic acid peroxide, vinyltris-(t-butylperoxy)silane, and the like. The amount of organic peroxide added varies depending on the amount of crosslinking aid added, but is generally preferably 0.1 to 10 parts by weight per 100 parts by weight of modified polypropylene. If the amount of organic peroxide added is less than 0.1 parts by weight, the degree of crosslinking will be low, and if it exceeds 10 parts by weight, decomposition will occur and the effect of improving high temperature heat resistance will be small, which is not preferable.

In the present invention, a polypropylene composition is obtained by mixing the above-described modified polypropylene, a crosslinking aid, an organic peroxide, and, if necessary, unmodified polypropylene, other polymeric substances other than polypropylene, fillers, and other additives. Mixing is carried out using a tumbler blender, a V-type blender, a Henschel mixer, a ribbon mixer, or the like. In some cases, the mixture may be melt-kneaded using a screw extruder, mixing roll, Banbury mixer, etc. at a temperature higher than the melting point of the modified polypropylene and lower than the 1-minute half-life temperature of the organic peroxide.

In the present invention, in order to laminate the modified polypropylene composition and metal with good adhesion, it is important to press the composition at a temperature that is higher than the melting point of the modified polypropylene and lower than the 1-minute half-life temperature of the organic peroxide.
Next, in the present invention, in order to impart high temperature heat resistance to the pressed laminate, it is extremely important to heat it to a temperature equal to or higher than the one-minute half-life temperature of the organic peroxide.
The heating time varies depending on the decomposition temperature of the organic peroxide, but generally 10 seconds to 30 minutes is appropriate. Heating can be performed by once cooling the laminate to room temperature and then reheating it, or by heating the laminate successively after thermocompression bonding of the laminate.

In addition, the present invention involves forming the modified polypropylene composition in advance into a sheet shape at a temperature lower than the one-minute half-life temperature of the organic peroxide, and then heating it all at once at a temperature higher than the one-minute half-life temperature of the metal and organic peroxide. It is also possible to press it.

There are no particular restrictions on the metals used for lamination; iron, aluminum, chromium, nickel, gold,
Examples include silver, copper, magnesium, zinc, tin, lead, steel, stainless steel, galvanized iron, and tinplate, with iron and aluminum being preferably used.

The polypropylene/metal laminate obtained in the above manner has strong adhesive strength between the two, excellent high-temperature heat resistance, and has both the excellent characteristics of polypropylene and the excellent characteristics of metal. It also has excellent new features that other manufacturers do not have, making it suitable for automobile materials, industrial materials,
It can be effectively used as building materials, beverage cans, packaging materials for various foods, etc.

Examples of the laminate of the present invention are shown below, but the present invention is not limited thereto.

In Examples, the adhesive strength and high temperature heat resistance of the obtained laminates were measured by the following methods.

Adhesive strength is measured between two 2cm wide metal sheets.
It is expressed as T-peel strength of a three-layer laminate with a layer of modified polypropylene composition 0.1 mm thick. The measurement is
The test was carried out at 23°C and 50% RH at a tensile speed of 20 mm/min.

The measurement of high temperature heat resistance was carried out between two metal sheets facing each other so that the overlap length was 2 cm.
A three-layer laminate with a modified polypropylene composition layer of 0.1 mm thickness was placed in an oven at 200°C, one metal sheet was suspended by a wire, and after 10 minutes, a load of 200 g was applied to the lower metal sheet, and both metal sheets were suspended. It is expressed as the time until the sheet separates. The thickness of the metal sheets is 0.2 mm for the iron sheet and 0.1 mm for the aluminum sheet, and these are sufficiently degreased.

Example 1 MFI=0.6 g/10 min, 100 parts by weight of propylene-ethylene random copolymer with ethylene content of 2.0% by weight, 2 parts by weight of maleic anhydride, 2,5-dimethyl-2,5-di(t-butyl) (peroxy)-hexane 0.12 parts by weight, butylated hydroxytoluene 0.1
Part by weight and 0.1 part by weight of calcium stearate were mixed in a Henschel mixer for 5 minutes, and L/D = 24.
Melt-kneading pelletization was performed at 220° C. using a 40 mmφ extruder, and then heat treatment was performed at 145° C. for 4 hours using a constant temperature dryer to obtain modified polypropylene. This modified polypropylene contained 0.5% by weight of maleic anhydride grafted therein.

15 parts by weight of this modified polypropylene, MFI=4.0
g/10 min, unmodified propylene-ethylene random copolymer with ethylene content of 3.0% by weight (melting point 140
°C) 85 parts by weight, divinylbenzene 10 parts by weight, dicumyl peroxide (1 minute half-life temperature 179 °C) 2.0
Part by weight, 0.1 part by weight of butylated hydroxytoluene, and 0.1 part by weight of calcium stearate were mixed in a Henschel mixer for 5 minutes, and a sheet with a thickness of 0.1 mm was formed at 165°C using an extruder equipped with a T-die.

This sheet was sandwiched between 2 cm wide aluminum sheets and pressed together at a temperature of 170° C. and a pressure of 10 kg/cm ² for 5 minutes, and then heated at 220° C. for 5 minutes. The adhesive strength of the laminate thus obtained is
7.5Kg/2cm, high temperature heat resistance was over 1 hour.

Comparative Example 1 The same procedure as in Example 1 was conducted except that benzoyl peroxide (1 minute half-life temperature: 130° C.) was used instead of dicumyl peroxide. When extruding a sheet, the extrudate became flaky and no sheet could be obtained.

Comparative Example 2 The same procedure as in Example 1 was carried out except that the sheet extrusion temperature was changed to 220°C. The extrudate became flaky and no sheet was obtained.

Comparative Example 3 The same procedure as in Example 1 was conducted except that modified polypropylene was not added and 100 parts by weight of unmodified propylene-ethylene random copolymer was used. The adhesive strength of the obtained laminate was 0.

Comparative Example 4 The same procedure as in Example 1 was carried out except that dicumyl peroxide was not added. The adhesive strength of the obtained laminate was 0.5Kg/2cm.
High temperature heat resistance was 50 seconds.

Comparative Example 5 The same procedure as in Example 1 was carried out except that divinylbenzene and dicumyl peroxide were not added. The resulting laminate had an adhesive strength of 1.8 kg/2 cm and a high temperature resistance of 90 seconds.

Example 2 15 parts by weight of modified polypropylene obtained in Example 1, MFI = 1.5 g/10 min, 85 parts by weight of unmodified propylene ethylene block copolymer with ethylene content of 2.7% by weight (melting point 160°C), average particle size 1.2 40 parts by weight of calcium carbonate of μ, 20 parts by weight of liquid 1,2-polybutadiene with a number average molecular weight of 1000, 2,5-dimethyl-2,5-di-(t-butylperoxy)-hexyne-3 (halved in 1 minute) temperature 193℃) 3 parts by weight,
0.1 part by weight of butylated hydroxytoluene and 0.1 part by weight of calcium stearate were mixed for 5 minutes using a Henschel mixer, and then melt-kneaded and pelletized using a CCM extruder at 170°C. A sheet having a thickness of 0.1 mm was formed from the obtained modified polypropylene composition pellets at 175 DEG C. using an extruder equipped with a T-die.

Sandwich this sheet between 2cm wide iron sheets,
Pressure bonding was carried out at a temperature of 220°C and a pressure of 10 kg/cm ² for 10 minutes. The adhesive strength of the laminate thus obtained is
13.5Kg/2cm, high temperature heat resistance was over 1 hour.

Comparative Example 6 In Example 2, 2,5-dimethyl-2,5
The procedure of Example 2 was repeated except that benzoyl peroxide was used instead of -di-(t-butylperoxy)-hexyne-3. During pelletization using a CCM extruder, the extrudate became flaky and good pellets could not be obtained.

Comparative Example 7 The same procedure as in Example 2 was carried out except that the sheet extrusion temperature was changed to 220°C. The extrudate became flaky and no sheet was obtained.

Comparative Example 8 The same procedure as in Example 2 was carried out except that the modified polypropylene was not added and 100 parts by weight of the unmodified propylene-ethylene block copolymer was used. The adhesive strength of the obtained laminate was 0.

Comparative Example 9 In Example 2, 2,5-dimethyl-2,5
The same procedure as in Example 2 was carried out except that -di-(t-butylperoxy)-hexyne-3 was not added. The adhesive strength of the obtained laminate was 0.3Kg/2cm.
High temperature heat resistance was 30 seconds.

Comparative Example 10 In Example 2, liquid 1,2-polybutadiene and 2,5-dimethyl-2,5-di-(t-
butylperoxy)-hexyne-3 is not added,
Other than that, the same procedure as in Example 2 was carried out. The adhesive strength of the obtained laminate was 9.7Kg/2cm, and the high temperature resistance was
It was hot in 120 seconds.

Claims (1)

[Claims] 1 Consists of a modified polypropylene partially or wholly grafted with unsaturated carboxylic acids, a crosslinking aid, and an organic peroxide whose 1-minute half-life temperature is 10°C or more higher than the melting point of the modified polypropylene. After pressing the polypropylene composition and the metal at a temperature higher than the melting point of the modified polypropylene and lower than the 1-minute half-life temperature of the organic peroxide, 1 of the organic peroxide is
A method for producing a laminate comprising a polypropylene resin layer and a metal layer, the method comprising heating to a temperature equal to or higher than the half-life temperature for minutes. 2 The laminate is a metal layer/polypropylene resin layer/
The manufacturing method according to claim 1, which is a metal layer. 3. The manufacturing method according to claim 1, wherein the unsaturated carboxylic acid is maleic anhydride. 4. The manufacturing method according to claim 1, wherein the crosslinking aid is liquid 1,2-polybutadiene or divinylbenzene. 5. The manufacturing method according to claim 1, wherein the metal is iron or aluminum. 6 The polypropylene composition was treated with organic peroxide.
The manufacturing method according to claim 1, which is used as a sheet-like product formed at a temperature lower than the half-life temperature in minutes.