Adhesive compound

Abstract

The invention relates to an adhesive compound containing a multi-armed vinyl aromatic block copolymer, one or more adhesive resins, and one or more auxiliary crosslinking agents. The invention also relates to an adhesive means comprising said adhesive compound and a carrier material and/or a cover. The invention also relates to a method for producing such an adhesive means. Compared to adhesive systems known up until now, such an adhesive means demonstrates clearly improved adhesion to hard, non-polar surfaces such as, for example, novel coated surfaces in the automotive industry.

Claims

1. An adhesive compound containing: at least one multi-armed vinyl aromatic block copolymer with more than 10 side arms; at least one adhesive resin; and at least one auxiliary crosslinking agent, wherein the adhesive compound contains: 10-80% of the at least one multi-armed vinyl aromatic block copolymer with more than 10 side arms, 20-90% of the at least one adhesive resin and a soft resin, 0.05-5% of the at least one auxiliary crosslinking agent, and 0.05-5% of further additives including antioxidants and/or UV protection agents, wherein the percentages add up to 100.

2. The adhesive compound according to claim 1, characterized in that the at least one multi-armed vinyl aromatic block copolymer is an elastomer from a group of styrene block copolymers (SBC).

3. The adhesive compound according to claim 1, characterized in that at least one adhesive resin is an aromatic hydrocarbon resin.

4. The adhesive compound according to claim 1, characterized in that the at least one auxiliary crosslinking agent has a general formula selected from: a) R.sup.1.sub.nCXR.sup.2.sub.m, wherein R.sup.1 represents any hydrocarbon chain and R.sup.2 represents terminal acrylate groups which are bonded to the central hydrocarbon atom X via an interim chain X, with 2m4 and n=4-m, or b) R.sup.1.sub.nR.sup.2.sub.mCXCR.sup.1.sub.nR.sup.2.sub.m, wherein R.sup.1 represents any hydrocarbon chains, R.sup.2 represents terminal acrylate groups which are bonded to the C atom via an interim chain, and X is any further arbitrary interim chain which links the two C atoms, with 1m3 and n=3-m.

5. The adhesive compound according to claim 4, characterized in that the at least one auxiliary crosslinking agent is a diacrylate monomer, a triacrylate monomer, a tetraacrylate monomer, or a high-numbered acrylate monomer.

6. The adhesive compound according to claim 1, characterized in that the adhesive compound contains at least one further adhesive resin and/or soft resin.

7. The adhesive compound according to claim 1, characterized in that the adhesive compound contains the antioxidants.

8. The adhesive compound according to claim 1, characterized in that the adhesive compound contains the UV protection agents.

9. The adhesive compound according to claim 1, which has been irradiated with electron beams.

10. An adhesive compound obtained from irradiating the adhesive compound according to claim 1 with electron beams.

11. An adhesive means containing: an adhesive compound according to claim 1; and a carrier material and/or a cover.

12. The adhesive means according to claim 11, characterized in that the carrier material is a thermoplastic foam carrier which contains polyethylene, polyethylene vinyl acetate, polyurethane or mixtures thereof.

13. The adhesive means according to claim 11, characterized in that the carrier material is a thermoplastic foam carrier which has a specific gravity of more than 50 kg/m.sup.3.

14. The adhesive means according to claim 11, characterized in that the cover is a siliconized or non-siliconized sheet which contains polyester, polyethylene, polypropylene and/or polyethylene terephthalate.

15. The adhesive means according to claim 11, characterized in that a first side and a second side of the adhesive means is adhesive, wherein the adhesive compound is on at least the first side.

16. The adhesive means according to claim 11 obtained from irradiating the adhesive compound with electron beams.

17. A method for producing an adhesive means, the method comprising: (a) forming the adhesive compound of claim 1; (b) applying the product from step (a) to a carrier material and/or a cover; and (c) irradiating the product from step (b) with electron beams.

18. The method according to claim 17, characterized in that a solvent is added in step (a).

19. The method according to claim 17, characterized in that no solvent is added in step (a).

20. A method of using the adhesive compound according to claim 1 for adhering to coated surfaces.

Description

DESCRIPTION OF THE FIGURES

(1) The adhesive means is explained below in more detail using FIG. 1, without wishing to be limited by this exemplary representation in the teaching according to the invention. FIG. 1 shows an adhesive means according to the invention with cover (A), adhesive compound (B), carrier material (C) and adhesive (D).

(2) In the production examples named below, the following test methods are used for validation. Parts always relates to parts by weight.

(3) Determination of the Gel Value:

(4) Approx. 0.2 g is weighed in from the transfer film (see examples) and this is added to a sealable glass flask. 50 mL toluene is added, and stirred. The mixture is left to stand for 2 days at room temperature. The crosslinking part swells, while the non-crosslinked part dissolves in the toluene. After 2 days, filtration takes place through a nylon filter (50-m nylon filter, Eaton Sentinel NMO-50-PO1Z-60L). The weight of the filter is determined in advance. After filtration, subsequent rinsing with ample toluene takes place. The filter residue is dried at 110 C. for 4 h. Thereafter, the filter and residue is weighed. The gel value is calculated from the ratio of filter residue and weighed-in quantity. The measured value is the average of 3 individual measurements.

(5) SAFT Test:

(6) The transfer film is likewise used to measure the SAFT (shear adhesion failure temperature). This is laminated on an etched polyester sheet (thickness of 50 m). Sample strips (width 25 mm) are cut from this. On a stainless steel plate (stainless steel according to Afera standard 4001, cleaned with gasoline in advance) the sample strip is stuck from the edge of the plate such that an area of 25 mm25 mm is stuck. Then, rolling takes place twice over the sample strip (5 m/min) using a roller (weight 5 kg). The sample strip is heated for 10 min, vertically loaded with 1 kg (shearing load), and this arrangement is hung in a convection oven. A temperature program varies the temperature from 30 C. to 200 C. with a heating rate of 2K/min. The test result is the temperature at which the adhesive strip falls off. A cohesive fracture results from the shearing of the adhesive compound. The measured value is the average of 3 individual measurements.

(7) Peel Strength 90

(8) The measurement of 90 peel strength is carried out with the foam adhesive tape (see examples). It takes place according to DIN ISO 1939 to in a standard atmosphere (23 C., 50% relative humidity). The substrate (aluminum sheet with 3-layer build-up of paint: filler, base coat and, as clear paint: 2K clearcoat ApO 1.2 from PPG) is wiped with a gasoline-soaked cloth and left to evaporate off. A 25-mm wide sample strip is applied to the substrate. The adhesive rear side is covered with an etched polyester sheet (thickness 50 m). Then, rolling takes place twice over the sample strip (5 m/min) using a roller (weight 5 kg). The specimen is conditioned for 10 min or 24 hours in a standard atmosphere (23 C., 50% humidity) and then the force, which must be applied at a peeling angle of 90 at a speed of 100 mm/min, is measured in order to remove the adhesive tape from the substrate. In an adhesive tape with a foam carrier, the adhesion of the adhesive compound to the substrate should be great enough that it is more than the internal strength of the foam support. The foam then splits. Cohesion fracture and normal fracture with residues on the substrate then occur as further fracture patterns. The measured value is the average of 3 measurements.

(9) Shear Strength at 23 C./4h

(10) The foam adhesive tape is likewise used to measure this shear strength (see examples). The 25-mm wide strip of adhesive tape is prepared as in the SAFT test on stainless steel. The specimen is loaded, hanging vertically with different weights, in a standard atmosphere (23 C., 50% relative humidity). After 4 hours it is checked whether the arrangement is still holding or whether the adhesive strip has sheared off. The value for the shear strength is then the weight (in N) at which the strip remains in place. It is tested in steps of 10N. The measured value is the average of 3 individual measurements.

(11) Shear Strength at 70 C.

(12) The same specimen as in the shear strength test at 23 C. is used to measure this shear strength. The specimen is loaded with a weight of 500 g hanging vertically in a convection oven at 70 C. The time is measured until the strip shears off and falls. The measured value is the median of 3 individual measurements.

EXAMPLES

Example 1 (B1)

(13) 33 parts of the styrene block copolymer Kraton HT 1200 (multi-armed styrene block copolymer, branching more than 10 arms, star-shaped, Kraton Polymers) was dissolved in 300 parts of a solvent mixture of gasoline and methyl ethyl ketone (80:20). To this were added 24.5 parts Novares NTA 100 (phenolically-modified aromatic hydrocarbon resin), 20.5 parts Regalite 1125 (hydrogenated aliphatic hydrocarbon resin, adhesive resin) and 20.5 parts Regalite 1010 (hydrogenated aliphatic hydrocarbon resin, soft resin, both from Eastman). As further components 0.5 parts Sartomer SR 351 (TMPTA, crosslinker, Arkema) and 0.5 parts Irganox 1010 (phenolic antioxidant, BASF) were added. The mixture was stirred until homogeneity was achieved. The resulting solvent adhesive compound was scratched out on a siliconized polyester sheet (thickness 50 m) by means of steel blades, firstly at room temperature for 10 minutes, and then dried in the convection oven for 5 min at 110 C. The thickness of the scratch was chosen such that the application weight after drying is 90 g/m.sup.2. The adhesive film was covered with a further siliconized polyester sheet (thickness 50 m) and subjected to electron radiation (180 kV, 60 kGy) in a nitrogen atmosphere. A transfer film was thus obtained. Both sides of the transfer film were laminated on a carrier foam to produce the adhesive tape according to the invention. The carrier foam (black, closed-cell, polyethylene foam, Alveo, TMA, specific gravity 125 kg/m.sup.3, thickness 0.65 mm) was firstly pre-treated on both sides with corona radiation. The transfer film was then laminated onto both sides such that the adhesive sheets were transferred onto the foam.

Comparative Example 1 (VB1)

(14) As example 1, but without the addition of Sartomer SR 351.

Comparative Example 2 (VB2)

(15) As example 1, but without electron radiation.

Comparative Example 3 (VB3)

(16) As example 1, but a linear SIS (Kraton D 1161) was used as styrene block copolymer.

Comparative Example 4 (VB4)

(17) As example 1, but a linear SBS (Kraton D 1101) was used as styrene block copolymer.

Comparative Example 5 (VB5)

(18) As example 1, but a linear SEBS (Kraton G 1657) was used as styrene block copolymer.

Comparative Example 6 (VB6)

(19) As example 1, but a radial SIS with approximately 4 arms (Kraton D 1124) was used as styrene block copolymer.

Comparative Example 7 (VB7)

(20) As example 1, but a radial, approximately four-armed SIS (Vector 4187 A from Dexco, approx. 78% diblock proportion) was used as styrene block copolymer.

Comparative Example 8 (VB8)

(21) As example 1, but a further radial, approximately four-armed SIS (Vector 4230 A from Dexco, approx. 30% diblock proportion) was used as styrene block copolymer.

Example 9 (B9)

(22) As example 1, but Miramer M 200 (hexamethylene diacrylate) from Miwon Commercial was used in the same concentration as crosslinker instead of Sartomer SR 351.

Example 10 (B10)

(23) As example 1, but instead of Sartomer SR 351, Laromer TPGDA (tripropylene glycol diacrylate) from BASF was used as crosslinker in the same concentration.

Example 11 (B11)

(24) As example 1, but instead of Sartomer SR 351, Ebecryl 40 (polyol tetraacrylate) from Allnex was used as crosslinker in the same concentration.

(25) TABLE-US-00001 a) Gel values (crosslinked proportion) and SAFT (shear adhesion failure temperature) values B1 VB1 VB2 VB3 VB4 Gel value in % 33 approx. 0 approx. 0 approx. 0 approx. 0 SAFT in C. 122 77 72 85 82 VB5 VB6 VB7 VB8 B9 B10 B11 Gel value in % approx. 0 approx. 0 approx. 0 approx. 0 35 38 37 SAFT in C. 77 84 77 77 117 116 127

(26) TABLE-US-00002 b) Peel strengths and shear strengths B1 VB1 VB2 Peel strength 90 after 15 N/cm 14 N/cm 15 N/cm 10 min Peel strength 90 after 20 N/cm 20 N/cm 20 N/cm 24 h Shear strength at 180 N 180 N 180 N 23 C./4 h Shear strength at 70 C. >360 h 1 h <1 h (500 g/625 mm.sup.2)

(27) Table a) shows that only the adhesive compound according to the invention according to Ex. 1 could be crosslinked with electron beams, thus resulting in a significant gel proportion and increased SAFT value. Mixtures with block copolymers with fewer side arms could likewise not be crosslinked (VB3 to VB8). Other multifunctional, terminal acrylate monomers can also be used (B9 to B11) as auxiliary crosslinking agents, in addition to Sartomer SR 351. Table b) shows that only adhesive compounds according to the invention lead to adhesive means which display both good peel strengths and also good shear strengths at increased temperatures.