Tackifier for rubber compositions

Abstract

A tackifier comprising a resin with repeating units of formula (I) wherein R.sup.1 is a linear or branched alkylen group with 1 to 10 carbon atoms and R.sup.2 is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with up to 20 carbon atoms and a non-aromatic compound which consists to at least 50% by weight of one or more linear or branched, saturated or unsaturated aliphatic hydrocarbon groups with at least 4 carbon atoms. ##STR00001##

Claims

1. A tackifier, comprising: a resin with repeating units of the following formula I: ##STR00006## wherein R.sup.1 is a linear or branched alkylen group with 1 to 10 carbon atoms and R.sup.2 is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with up to 20 carbon atoms; and a non-aromatic compound comprising at least 50% by weight of one or more linear or branched, saturated or unsaturated aliphatic hydrocarbon groups with at least 4 carbon atoms; wherein the non-aromatic compound is a fatty acid or a fatty alcohol, and wherein the tackifier is solid, and wherein the tackifier has a glass transition temperature in the range of 60° C. to 150° C.

2. The tackifier of claim 1, wherein R.sup.1 in formula I is CH.sub.2, HC—CH.sub.3 or H.sub.2C—CH.sub.2.

3. The tackifier of claim 1, wherein R.sup.2 in formula I is a linear or branched, saturated or unsaturated aliphatic hydrocarbon group with 4 to 10 carbon atoms.

4. The tackifier of claim 1, wherein the resin is obtained by reacting acetylene and para tertiary butyl phenol.

5. The tackifier of claim 1, wherein the non-aromatic compound comprises at least 80% by weight of linear or branched, saturated or unsaturated, aliphatic hydrocarbon groups with from 10 to 60 carbon atoms.

6. The tackifier of claim 1, wherein the tackifier comprises 0.1 to 50 parts by weight of the non-aromatic compound per 100 parts by weight of the resin of formula I.

7. The tackifier of claim 1, wherein the tackifier comprises at least 80% by weight of the resin of formula I and the non-aromatic compound.

8. A process of preparing the tackifier of claim 1, the process comprising: adding the non-aromatic compound to a melt of the resin, to obtain a mixture, and converting the obtained mixture into solid granules by pastillation.

9. The process of claim 8, wherein the melt of the resin is molten and has a temperature of 150 to 250° C.

10. A process of preparing a rubber composition, the process comprising adding the tackifier of claim 1 to the rubber.

11. The tackifier of claim 1, wherein the resin comprises units of the following formula II: ##STR00007## wherein R.sup.2 in formula II is para tertiary butyl.

12. The tackifier of claim 1, wherein the resin comprises units of the following formula III: ##STR00008## wherein R.sup.2 in formula III is para tertiary butyl.

13. The process of claim 10, wherein the tackifier is added to the rubber at a temperature in the range of 60 to 150° C.

Description

EXAMPLES

(1) Procedure for Preparation of Various Mixtures of Koresin and the Non-Aromatic Compound:

(2) Koresin® (200 g) and the non-aromatic compound (in amounts specified in Table 1) were place in a flask equipped with a condenser and mechanical stirrer and heated up to 200° C. The Mixture was then stirred for 3 hours and then cooled down. After the melt had cooled down and solidified the material was removed and analyzed via DSC (Differential scanning calorimetry). The glass-transition temperatures (Tg) were the derived from the DSC data.

(3) TABLE-US-00001 TABLE 1 Amount non- aromatic compound in parts by weight Experiment per 100 parts by Tg Number Additive weight of Koresin [° C.] 1 — — 110 2 Undecylenic acid 3 94.8 3 Undecylenic acid 5 88.8 4 Undecylenic acid 7 81.9 5 Stearic acid 3 101 6 Stearic acid 5 112 7 Stearic acid 7 87 8 PIBSA* 3 101.8 9 PIBSA* 5 97.9 10 PIBSA* 7 96.8 11 Stearyl alcohol 5 91.7 12 Stearyl alcohol 7 69.1 13 Stearyl alcohol 8 69.5 14 Stearyl alcohol 9 68.5 15 Stearyl alcohol 10 63.7 *the PIBSA used was Glissopal ® SA from BASF
Determination of Tackiness

(4) A rubber formulation with the following composition (in parts by weight) was used:

(5) TABLE-US-00002 SBR rubber 100 Process oil 13 Carbon black 45 Talc 17 Polybutadiene 17

(6) The above rubber formulation was compounded on a roller mill with 5 parts by weight of Koresin® (example 1) or of the same amount of mixtures according to example 7 (7 parts by weight of stearic acid), respectively of example 11 (5 parts by weight of stearyl alcohol). After the addition of the tackifier the temperature of the mixture was raised to 120° C. for 3 minutes to ensure a homogenous dispersion of the resin.

(7) Test samples prepared from the finished compound were stored at 23° C. and a relative humidity of 50% for the times given in Table 2.

(8) The tack of the test samples was determined after different storage times as listed in Table 2.

(9) In particular, the tack of these samples was measured with a “Ketjen Tackmeter”. Two test samples which had the form of strips are pressed together with a force of 20 N/cm.sup.2 for 30 seconds. Between the samples there was a Teflon foil with a window to ensure a defined contact area. After release of the force and another 10 seconds for relaxation the strips were separated. The force to separate the two rubber strips from each other was measured in newton (N). A high force corresponds to a high tackiness of the test samples.

(10) TABLE-US-00003 TABLE 2 Tackiness Rubber Rubber formulation formulation Rubber Rubber with with formulation formulation tackifier of tackifier of Storage without with example example (days) tackifier Koresin 11 7 0 16 18 18 17 1 15 31 25 27 3 11 15 16 13 6 7 11 11 9