DE3230715C2 - Composite with a polypropylene substrate and process for its manufacture - Google Patents

Description

Usually polypropylene is made with polar polymers, such as nylon, ethylene / vinyl alcohol copolymers (EVOH) or polyvinyl alcohol polymers, as well as with metals, such as aluminum, steel, copper, tin, brass etc., glued by making a mixture of one Polypropylene, on which an unsaturated carboxylic acid or an acid derivative is grafted on, and polypropylene as an intermediate layer. This material will directly as an adhesive layer between the polypropylene and the polar substrate.

It would often be an advantage to have a polyethylene, to an unsaturated carboxylic acid or a Acid derivative is grafted on, could use because this is very easy in a melt reaction system can be manufactured. You mix it up the polyethylene graft copolymers with polypropylene, then you only get one proportionally weak bonding with polar polymers and others polar substrates. In some cases, at all no sticking between the mixture the graft copolymer and the polypropylene and achieved the polar substrate. With the methods of present invention and the resulting Composite materials become the difficulties identified overcome.

According to the teaching of the present invention one by grafting on suitable unsaturated ones Carboxylic acids or acid derivatives, e.g. B. anhydrides, on polyethylene and mixing the resulting Graft copolymers with a mixture of polyethylene and an elastomer, according to the type and amount stated in the claim, of excellent adhesive Adhesion to polypropylene and various  Substrates, including polar polymers such as Nylon, ethylene / vinyl alcohol copolymers, polyvinyl alcohol polymers and copolymers, on metals, Glass, paper, wood and the like substrates. The elastomer helps to improve the bond strength of the mixture with the polypropylene substrate is crucial at, since without his presence only a weak one Adhesion to polypropylene is achieved. This result could not be provided by the specialist and must therefore be described as surprising. All the more so than it used to be in this construction of the glue Presence of polypropylene in the adhesive is not required.

The expression polyethylene as used in this description of the invention for the backbone, on that is grafted, used, includes homopolymers of ethylene and copolymers of ethylene with Propylene, butene (1) and other unsaturated aliphatic Hydrocarbons. The ethylene polymer should preferably be linear. It is also recommended occasionally on mixtures of two or more to graft these homopolymers and copolymers.

The term polyethylene polymer as used in this Description of the invention is used, should Denote mixed resin, the ethylene homopolymer and Copolymers of ethylene with other unsaturated Includes hydrocarbons with higher molecular weight Olefins such as propylene, butene- (1) and hexene- (1). It is occasionally advantageous to use mixtures of two or more of the above homopolymers or to use copolymers in the mixed resin.

The polyethylene homopolymers or copolymers can be made by any known method be in which transition metal catalysts and low or medium pressures are applied or where radical initiators and high pressures be applied. Accordingly, the polymers low density polyethylene, linear  Low density polyethylenes, from polyethylenes medium density or high polyethylene Density exist.

The term "elastomers" is intended to include copolymers from ethylene and an alpha-olefin, terpolymers from ethylene, an alpha olefin and a diene, Homopolymers of isobutylene, copolymers of Isobutylene, homopolymers of chloroprene, copolymers from a diene and a vinyl aromatic compound, Block copolymers of a diene and one vinyl aromatic compound, copolymers of one hydrogenated diene and a vinyl aromatic compound, hydrogenated block copolymers from one Diene and a vinyl aromatic compound, homopolymers of butadiene and copolymers from one ethylenically unsaturated nitrile and a diene.

Examples of these elastomers are given Copolymers of ethylene and propylene, terpolymers from ethylene, propylene and a diene, copolymers made of isobutylene and isoprene, chlorinated copolymers from isobutylene and isoprene, copolymers from butadiene and styrene, copolymers of butadiene and vinyl toluene, Block copolymers of butadiene and styrene, block Copolymers of butadiene and vinyl toluene, block Copolymers of isoprene and styrene, block copolymers from isoprene and vinyl toluene, hydrogenated copolymers from butadiene and styrene, hydrogenated block copolymers from butadiene and styrene, hydrogenated block copolymers made of isoprene and styrene, styrene / ethylene / butylene / Styrene block copolymers, copolymers of acrylonitrile and butadiene, copolymers of methacrylonitrile and Butadiene, copolymers of acrylonitrile and isoprene and copolymers of methacrylonitrile and isoprene.  

In the present invention, it is recommended the use of ethylene / propylene copolymers, Ethylene / propylene / diene terpolymers, homopolymers of Isobutylene, chlorinated copolymers of isobutylene and isoprene, homopolymers of chloroprene, hydrogenated Block copolymers of styrene and butadiene and styrene / ethylene / butylene / styrene block copolymers.

To the unsaturated carboxylic acids or acid derivatives, which are used as graft monomers Connections like Acrylic acid, fumaric acid, methacrylic acid, Maleic acid, itaconic acid, citraconic acid, Mesaconic acid, maleic anhydride, citraconic anhydride, Itdaconic anhydride, 4-methylcyclohex-4-en- 1,2-dicarboxylic anhydride, bicyclo (2.2.2) oct-5-en- 2,3-dicarboxylic anhydride, 1,2,3,4,5,8,9,10-octahydronaphthalene 2,3-dicarboxylic anhydride, 2-oxa-1,3- diketospiro (4.4) -non-7-ene, bicyclo (2.2.1) hept-5-ene-2,3- dicarboxylic anhydride, maleopimaric acid, tetrahydrophthalic anhydride, x-methylnorborn-5-en-2,3-dicarboxylic anhydride, Norborn-5-en-2,3-dicarboxylic anhydride, endo-cis-5-norbornene-2,3-dicarboxylic acid anhydride (Nadic anhydride), cis-exo-5-norbornene-2,3-dicarboxylic acid anhydride (Himic anhydride), methyl-cis-exo- 5-norbornene-2,3-dicarboxylic acid anhydride (methyl Himic anhydrides), methyl-endo-cis-5-norbornene-2,3-dicarboxylic acid anhydride (methyl nadic anhydride), and other Monomers with a fused ring system, as described in U.S. Patents 3,873,643 and 3,882,194, both of the applicant of the present application issued, are described. The head graft Copolymers described in this U.S. Patent 3,882,194 are suitable for the purposes of the present Invention. The working method for manufacturing of the graft copolymers are in the above described US-PSen described.  

Since these blends do not contain polypropylene, the discovery that the blends of the present invention adhere firmly to polypropylene is surprising. The following systems are examples of composite materials of the present invention:
Polypropylene / adhesive according to the invention / nylon,
Polypropylene / adhesive / ethylene-vinyl alcohol copolymer,
Polypropylene / adhesive / aluminum,
Polypropylene / adhesive / steel,
Polypropylene / adhesive / glass,
Polypropylene / adhesive / wood,
Polypropylene / adhesive / leather,
Polypropylene / adhesive / nylon / adhesive / polypropylene,
Polypropylene / Adhesive / EVOH / Adhesive / Polypropylene and
Polypropylene / adhesive / aluminum / adhesive / polypropylene.
Other metals such as copper, steel, brass, and the like can also be used.

It is true that DE-OS 26 58 547 already has it Composite materials by means of adhesive mixtures from Grafting of e.g. B. modified unsaturated acids Polyolefins and hydrocarbon elastomers made; meanwhile there is the one with the use of polypropylene related problems not addressed at all been and also the elastomer content expressly set the range from 1 to 30%. As a result, could this reference does not suggest that by increasing the proportion of elastomer achieve good adhesion to polypropylene substrates can and it is otherwise in this structure of the adhesive mixtures not otherwise with polypropylene substrates manufactured composite bodies considered necessary The use of adhesives containing polypropylene is required (cf. Introduction to the description). According to the registration in surprising Ways achievable are from the later ones following examples and comparative examples can be seen.

In the case of DE-OS 27 47 032, based on previous knowledge of inventors involved in the present case, then adhesive mixtures were described, which is a graft copolymer, an elastomer and a blending resin contain. But it follows from the relevant ones there Examples that the elastomer content between 5 and 30% is. The special circumstances with composite materials with polypropylene substrates are not addressed there, so that, in contrast, the solution now found for Production of polypropylene substrates containing good adhesion Composites by using an adhesive mixture with a high proportion of elastomer with an unexpected Success is connected. That improvement in liability the later test results show a surge.

For the preparation of the mixtures according to the invention from the above-mentioned graft copolymers Elastomers and the ethylene homopolymers and copolymers can any mixing device and Mixing technique can be applied. So they can Mixtures, for example, in an electrically heated one Brabender plastic order mixing head under Use of a screw mixer according to the following Conditions are established: temperature - 204 ° C, rotor speed - 120 revolutions per Minute and mixing time - 10 minutes after melting.

The resulting mixtures became films by approximately 0.127 to 0.178 mm in thickness. The films were then heat sealed on the substrate to be evaluated with a suitable  Temperature and in an appropriate time upset. These conditions are for

• 1. nylon 6 - 221 ° C and 2 seconds;
• 2. Ethylene / vinyl alcohol copolymer (EVOH) - 221 ° C and 5 seconds;
• 3. Polypropylene - 260 ° C and 5 seconds;
• 4. Aluminum - 221 ° C and 2 seconds.

The resulting composite materials were in the Tested in a way that they were in strips of 25.4 mm Cut width. The adhesive strength was then tested using a T-peel and lift-off test, which the in the ASTM regulation D 1876-72 test described corresponds.

Comparative Example 1

x-Methylbicyclo (2.2.1) hept-5-en-2,3-dicarboxylic anhydride (XMNA) is made with a polyethylene homopolymer resin high density in a twin screw extruder reacted to a graft copolymer resin to which 1.5 wt .-% XMNA are incorporated and which has a melt index of 1.5 g / 10 min. The graft copolymer is changing in Quantities with a propylene / ethylene copolymer, which is a random distribution of the linear and branched Has polymer parts and its Melt flow rate (MFR) is 2, mixed. These mixtures were through 2 seconds long heat sealing at 221 ° C on nylon upset. The results of the T-peeling or lifting tests are measured adhesive strengths compiled below:  

Comparative Example 2

Using the same graft copolymer, described in Example 1 became mixtures with a graft / ethylene block copolymer, which had a melt flow rate (MFR) of 2, produced.

Comparative Example 3

The same mixtures as in Comparative Example 2 have been used for five seconds long heat sealing at 221 ° C on an ethylene / vinyl alcohol Copolymer (EVOH) applied. All these mixtures showed extremely poor adhesion to EVOH. These patterns could not be tested be since they fell off.  

Comparative Example 4

90% of a propylene / ethylene block copolymer, containing 7.8% ethylene, 10% by weight of the same graft copolymers mixed together are described in Example 1. This mixture was applied to EVOH by heat sealing and gave a heat seal adhesive strength of 8.9 g / mm.

Comparative Example 5

When using 90% of a polypropylene homopolymer an MFR of 4 mixed with 10% of the in Example 1 described by graft copolymers Heat seals were applied to EVOH, as pointed out the composite material obtained is a heat seal Adhesive strength of 1.8 g / mm (0.1 lb / in). The same mixture is heat sealed on the polypropylene described in Comparative Example 1 Copolymers with random distribution of the linear and branched polymer parts applied, the adhesive strength is more than 179 g / mm.

The above examples show that when using a polyethylene graft copolymer a polypropylene homopolymer or one Block copolymer containing ethylene, the a random distribution of the linear and branched Has polymer components, is mixed, does not adhere to polar polymers is satisfactory.  

Examples 1 to 7 according to the invention

Mixtures were made using a low density polyethylene (LDPE) with a melt index of 1.8 g / 10 min., one Ethylene / propylene / diene monomer terpolymer (EPDM) - Elastomers and that described in Comparative Example 1 Graft copolymers. These blends were tested for their adhesive strength to an ethylene / Vinyl alcohol copolymers (EVOH), on a polypropylene Copolymers with random distribution of linear and branched polymer parts, aluminum and tested on nylon 6. The results are in the Table I compiled below.  

Table I

The results show that in the case where the mixtures contain at least 30% EPDM, excellent adhesive strength is achieved not only on ethylene / vinyl alcohol copolymers, Nylon 6 and aluminum, but also on polypropylene.

Examples 8 to 12 according to the invention

Mixtures were made using the same low density polyethylene as it is described in Examples 1 to 7, the same graft copolymer as in Comparative Example 1 and a styrene / ethylene / Butylene / styrene block copolymers (one under the Well known trade name "Kraton G 1650" Styrene / hydrogenated diene / styrene copolymer (SEBS)). The results regarding adhesive strength are compiled in Table II.  

Table II

Again, it allows the use of at least 30% of the elastomer the mixtures, solid on Glue polypropylene in addition to gluing the ethylene / vinyl alcohol copolymer, nylon 6 and Aluminum.

Examples 13 to 15 according to the invention

Mixtures were made from one High density polyethylene that has a melt index of 0.8 and has a density of 0.96+, and the same graft-modified HDPE, which in the Comparative Example 1 is described, as well as various Elastomers: that in the invention Examples 1 to 7 described EPDM, a Styrene / ethylene / butylene / styrene block copolymers, as described in Examples 8 to 12 and a polyisobutylene (PIB) (Vistanex L-80). The results summarized in Table III prove that mixtures containing 45% of the polyethylene high density, 45% of the elastomer and 10% of the modified high density graft copolymer contain an excellent adhesive strength all four substrates.  

Table III

Because a bond with polypropylene and polar Polymers can be made from numerous Composites, laminates and co-extrusion products made using these materials will. Composites, the polypropylene, the adhesive mixtures and nylon, aluminum or May contain ethylene / vinyl alcohol copolymers both by lamination and by co-extrusion getting produced.

Can in the manufacture of composite materials any technical work equipment to combine the two or more Use layers as are known per se to the person skilled in the art are. To the preferred ones Working methods include blown film co-extrusion, the cast film and film co-extrusion, the Blow molding-co-extrusion, lamination and co-extrusion coating. As another suitable Methods are powder coating, rotoforming Processes, profile co-extrusion, wire sheathing To lead co-extrusion and the like.

The abbreviations used in the description have the following meanings:

EVOH - ethylene / vinyl alcohol copolymers
XMNA - x-methylbicyclo (2.2.1) hept-5-ene-2,3-dicarboxylic acid anhydride
MFR - melt flow rate
HDPE - high density polyethylene
LDPE - low density polyethylene
EPDM - ethylene / propylene / diene monomer terpolymer
SEBS - styrene / ethylene / butylene / styrene copolymer with the trade name Kraton G 650
PIB - polyisobutylene

Claims (11)

1. A process for the production of composite materials which consist of a polypropylene substrate, a polar substrate and an adhesive mixture which is in intimate contact between these substrates, by bringing an adhesive mixture into contact with the polypropylene substrate and the polar substrate, the adhesive mixture consisting of

• a) a graft copolymer from about 70 to 99.999 wt .-% of a polyethylene base, which has been grafted with about 30 to 0.001 wt .-% of at least one serving as a graft, which in turn at least one unsaturated carboxylic acid or an acid anhydride or both types of compounds contains
• b) at least one elastomer, the elastomer in turn consisting of either copolymers of ethylene and an alpha-olefin, of terpolymers of ethylene, of an alpha-olefin and a diene, of homopolymers of isobutylene, of copolymers of isobutylene, of homopolymers of chloroprene , from copolymers of a diene and a vinylaromatic compound, from copolymers of a hydrogenated diene and a vinylaromatic compound, from homopolymers of butadiene or from copolymers of an ethylenically unsaturated nitrile and a diene and mixtures thereof and
• c) at least one polyolefin resin, which in turn consists of a homopolymer of ethylene, a copolymer of ethylene and an alpha-olefin or a mixture thereof,

characterized in that the adhesive mixture contains no polypropylene and the elastomer is present therein in an amount of at least 30% by weight of the mixture. 2. The method according to claim 1, characterized, that the elastomer mentioned in section b) in an amount of 40 to 65 wt .-% based on the total mixture. 3. The method according to claim 1, characterized, that the polyolefin resin mentioned in section c) is present in an amount of at least 25 % By weight of the mixture is present. 4. The method according to claim 1,  characterized, that the polyethylene base of the graft copolymer according to a) linear polyethylene contains low density. 5. Multi-component composite materials consisting of

• a) a polypropylene substrate
• b) a polar substrate and
• c) an adhesive mixture which bonds both components together, as claimed in one of claims 1 to 3 and 4.

6. The composite material according to claim 5, characterized, that the substrate according to b) consists of nylon. 7. The composite material according to claim 5, characterized, that the total number of components is more than three. 8. The composite material according to claim 5, characterized, that the composite material from the polypropylene / inventive system Adhesive mixture and either nylon or ethylene-vinyl alcohol copolymer consists. 9. The composite material according to claim 5, characterized, that the composite material consists of the polypropylene / adhesive / aluminum system. 10. The composite material according to claim 7, characterized, that the composite from the system Polypropylene / adhesive / intermediate layer / adhesive / polypropylene and as Intermediate layer of nylon or EVOH or aluminum is present.