Aliphatic petroleum-based resins and hot melt pressure sentitive adhesive containing same

Abstract: The invention provides a petroleum-based aliphatic resin having a) a Ring and Ball (R&B) softening point in the range of 75 to 110°C, b) a weight average molecular weight (Mw) of 1000 to 2600 Dalton, a z-average molecular weight (Mz) from 1900 to 5000 Dalton and an Mw/Mn below 2.0, c) a level of aromatic protons below 1.5 % with respect to the total protons determined by 1 H-NMR, and d) a mixed methylcyclohexane aniline cloud point (MMAP) of 90°C or less. The resins according to the invention are characterized by a high amount of cyclic structures. Further disclosed is a method of independently controlling the R&B softening point and the molecular weight of an aliphatic resin composition during its preparation by polymerization of a petroleum-based feed, the method being characterized in that the amount of cyclic structures in the resins is increased.

Description: This invention relates to aliphatic resins useful for tackifying purposes wherein the amount of cyclic, crosslinked or networked structures is increased and controlled in such a manner that a better relation between the R&B softening point and the molecular weight and a better compatibility to aromatic solvents is obtained. These resins have an improved adhesive performance in hot melt pressure sensitive adhesive compositions. Background of the Invention Hot melt pressure sensitive adhesives usually include a mixture of a polymer or copolymer (in the following, the term "polymer" will be used for both homopolymers and copolymers), preferably a block copolymer, a petroleum tackifier resin and optionally further components such as an extender oil (also named processing oil), fillers and some additives like antioxidants or colorants. The above polymer often is an S-I-S (styrene-isoprene-styrene) block copolymer having polystyrene and polyisoprene block segments. In such a case, the adhesive composition may additionally include some polystyrene-polyisoprene diblocks. The petroleum-based resin exerts an important influence on the physico-chemical properties of the adhesive such as its hot melt viscosity, compatibility to aromatic solvents, shear properties and tack properties. To attain the optimum profile of a low melt viscosity, good compatibility to organic solvents, high tack and shear properties without losing high temperature shear performance, conventional petroleum-based tackfying resins used to contain a certain amount of aromatic modifications. Prior art resins with no aromatic modification failed to attain the above properties to a satisfactory extent. The following patents and/or patent applications may be mentioned as related documents of interest: US 4,411,954 describes the use of aliphatic resins prepared as described in US 3,577,398 in S-I-S based hot melt pressure sensitive adhesives. EP 0 447 855 describes the use of aliphatic and aromatic modified aliphatic resin in S-I-S based hot melt pressure sensitive adhesives. The used levels of aromatic modification were between 11 and 15%, and styrene was mentioned as the aromatic monomer. US 4,623,698 describes the use of aliphatic and aromatic modified aliphatic resins with softening points from 0 to 80°C as tackifier in SB polymers. US 4,078,132 describes the preparation of aliphatic and aromatic modified aliphatic resins from heat-soaked piperylene streams. Isobutylene and isoamylene are described to act as chain transfer agent and alphamethylstyrene (AMS) is described to be used as a aromatic modifier. Some applications are described using resins with softening points between 70 and 85°C. WO 95/16755 describes a hot melt adhesive formulation using a S-I-S polymer, a aromatic modified aliphatic resin and an extender oil. The aromatic modification caused hot melt pressure sensitive adhesive formulations having a low viscosity and enhanced tack properties. Aromatic modified tackifying resins, however, are disadvantageous for a number of reasons. Firstly, aromates are relatively expensive and the use of no aromate would make the resin cheaper. Secondly, they are less suitable for hydrogenation, hydrotreatment and quenching processes to improve the resin colour, before they are used in any application. Thirdly, aromatic modified aliphatic resins result in lower shear performance at higher temperatures in hot melt based pressure sensitive applications. It would therefore be desirable and is an object of the present invention to provide a cheaper petroleum-based resin which exhibits similar or even better application properties than aromatic modified resins. A further object of the invention is to provide aliphatic resins which are useful in hot melt pressure sensitive adhesive compositions and combine a low melt viscosity with excellent tack and shear properties, and a hot melt pressure sensitive adhesive containing such resins. According to the invention, it was found that aliphatic resins having an increased amount of cyclic structures had the desired R&B softening points and molecular weights and resulted in a low viscosity hot melt pressure sensitive adhesive composition having excellent tack and shear properties without losing its high temperature shear performance. The resins of the present invention are particularly distinguished from aliphatic resins of the state of the art in that they contain a higher amount of cyclic structures. The term "cyclic structure" is defined as any structure feature which serves to increase the level of crosslinking or network structure in the resin. These types of structural features can be the result of, but are not limited by, the following reactions: back biting of its growing polymer chain to incorporate cyclic structures along a backbone and/or at chain termination, dimerization of monomers to produce reactive cyclic structures which can be incorporated in the polymer chains, intramolecular linking of pendent groups within a polymer chain, and crosslinking between short polymer chains to form highly networked structures. This is new in this field of application and can be confirmed by determining a number of physicochemical properties which are indicative for cyclic structures. SUMMARY OF THE INVENTION In view of the above, the present invention provides a petroleum-based aliphatic resin having a) a Ring and Ball (R&B) softening point in the range of 75 to 110°C b) a weight average molecular weight (Mw) of 1000 to 2600 Dalton, a z-average molecular weight (Mz) from 1900 to 5000 Dalton and an Mw/Mn below 2.0. c) a level of aromatic protons below 1.5 % with respect to all protons determined by 1 H-NMR. d) a mixed methylcyclohexane aniline cloud point (MMAP) of 90°C or less. In afurther embodiment, the invention provides a hot melt pressure sensitive adhesive composition comprising (i) 100 parts by weight of a Styrene-Isoprene-Styrene (S-I-S) rubber (ii) 70 - 200 parts by weight of a petroleum-based aliphatic resin having a Ring and Ball (R&B) softening point in the range of 75 to 110°C a weight average molecular weight (Mw) of 1000 to 2600 Dalton, a z-average molecular weight (Mz) from 1900 to 5000 Dalton and an Mw/Mn below 2.0 a level of aromatic protons below 1.5 % with respect to all protons determined by 1 H-NMR a mixed methylcyclohexane aniline cloud point (MMAP) of 90°C or less, and (iii) 0 - 70 parts by weight of an extender oil characterized in that the composition has a maximum viscosity of 100,000 mPas, preferably 80,000 mPas, measured according to ASTM method D3236 at 175°C with a Brookfield viscosity meter. Furthermore, this description discloses a method of controlling the R&B soften ing point and the molecular weight of an aliphatic resin composition, which method is characterized in that the amount of cyclic structures in the resins is increased. This increase can preferably be achieved by varying one or more of the following parameters in the polymerization reaction: (i) reaction temperature, (ii) amount of catalyst, (iii) amount of chain transfer agent, (iv) amount of cyclodiolefinic components in feed. Other objects and features of the invention will be apparent from the following detailed description and the appending claims. DETAILED DESCRIPTION OF THE INVENTION The petroleum-based resin used in this invention is preferably the Friedel-Crafts polymerization product of a cracked petroleum feed containing C5 olefins and diolefins or a mixture of C5 and C6 olefins and diolefins copolymerized with a C4 or C5 olefin or dimers thereof used as chain transfer agent. More preferably, the petroleum feed contains some cyclic diolefins like cyclopentadiene, methylcyclopentadiene, dicyclopentadiene and/or dimerization products of those and the active C5 and C6 components. The desired increase of the amount of cyclic structures in the aliphatic resins can e.g. be achieved by increasing the reaction temperature and/or the amount of catalyst and using a cyclodiolefinic rich feed stream. The increase of the amount of cyclic structures in the resin was confirmed by finding a higher R&B softening point and/or a lower molecular weight and by a better compatibility to aromatic solvents (lower MMAP). The tackifying resins according to this invention result in a lower melt viscosity of hot melt compositions wherein they are incorporated. Futhermore, they impart excellent tack and shear properties on these hot melt compositions. It is known that during the Friedel-Crafts polymerization of piperylene and/or isoprene besides 1,2 and 1,4 addition also a part of the monomers is cyclodimerized before polymerization or even cyclizises afterthe polymerization. Finding a higher R&B softening point together with a similar or even lower molecular weight, or a lower molecular weight at a similar or even higher R&B softening point indicates a higher amount of cyclic structures in the resin. It was found by the inventors that the amount of cyclic structures could be influenced by varying the polymerization conditions, like catalyst level, reaction temperature, amount of chain transfer agent and the feed composition. In the most preferred embodiment of the present invention, the aliphatic petroleum tackifier resin comprises a Friedel-Crafts polymerized petroleum feed comprising C5 and C6 olefins and/or diolefins, and preferably cycloolefins and cyclodiolefins, like cyclopentadiene, methylcyclopentadiene and their dimers copolymerized with a C4 or C5 olefins and/or dimers as chain transfer agent. The final adhesive application properties of such resins are optimized by controlling the amount of cyclic structures by varying the reaction temperature, the amount of catalyst, the amount of chain transfer agent and the feed composition. It is thus possible to obtain resins with a desired softening point and molecular weight distribution during the polymerization process. A higher degree of cyclic structures means a more rigid structure confirmed by finding a higher R&B softening point together with a similar or even lower molecular weight, or a lower molecular weight at a similar or even higher R&B softening point than in a resin having a lower amount of cyclic structures. It was also observed that such resins had a better compatibility in aromatic solvents, as could be seen by the lower MMAP cloud point. This was not due to any significant incorporation of aromatic components because the proton NMR analyses showed no differences between regular aliphatic resins and the resins prepared according to this invention. The ultimate resins of this invention have the following properties: a) an R&B softening point varying from 75 to 110°C, b) an Mw from 1000 to 2600 Dalton, a z-average molecular weight (Mz) from 1900 to 5000 Dalton and an Mw/Mn below 2.0, Mn indicating the number average molecular weight, c) a level of aromatic protons below 1.5 % with respect to all protons determined by 1 H NMR. d) an MMAP cloud point of 90°C or less. These polymerized resins can be used as tackifiers in hot melt pressure sensitive compositions which further comprise a polymer and optionally an extender oil and other adjuvants. A preferred hot melt pressure sensitive composition according to the invention comprises a mixture of: (i) 100 parts by weight of a styrene-isoprene-styrene (S-I-S) block copolymer like Kraton D 1107, Kraton D KX 601 Cs, Kraton D 1114, Vector 4111, containing about 10 to 30 parts per weight styrene. (ii) about 70 to 200 parts by weight per 100 parts polymer of a petroleum-based aliphatic resin having a) a Ring and Ball (R&B) softening point in the range of 75 to 110°C b) a weight average molecular weight (Mw) of 1000 to 2600 Dalton, a z-average molecular weight (Mz) from 1900 to 5000 Dalton and an Mw/Mn below 2.0 and c) a level of aromatic protons below 1.5 % with respect to all protons determined by 1 H NMR. In this embodiment, the petroleum tackifier resin (ii) to be included has an MMAP of 90°C of less. (iii) the mixture may also contain some extender oil in a amount of 0 to 70 parts by weight per 100 parts polymer, like Shellflex 451 FC The mentioned preferred hot melt composition has a melt viscosity at 175°C of less than 100,000, preferably less than 80,000 mPas measured according to ASTM-D3236 with a Brookfield viscosity meter. The use of the resin (ii) according to this embodiment in such a hot melt pressure sensitive adhesive composition results in a lower melt viscosity than the use of known aliphatic resins like Piccotac 95E and Escorez 1310, a rolling ball tack comparable to existing aliphatic or aromatic modified resins like Piccotac 95E or Escorez 2203 or Hercotac 1148 and a better high temperature shear strength than aromatic modified resins like Escorez 2203, Hercotac 1148 and Hercules RESIN A. The above commercial resins of which the trade names were given are described in more detail in the Experimental Section (Materials & Methods) below. Commonly, the resins of the present invention are prepared by Friedel-Crafts polymerization in which a mixture of a cracked petroleum feed and a chain transfer agent in an inert solvent is treated with 1.0 to 8.0 wt% of a catalyst such as aluminum chloride, aluminum bromide, aluminum fluoride, boron trifluoride, or solutions, slurries or complexes thereof, applying reaction temperatures between 0 and 100°C. The ultimate polymerization feeds normally contain about 20 to 60 and preferably 30 to 50 wt% of a petroleum feed stream, 0 to 20 wt% chain transfer agent and 40 to 80 wt% inert solvent like toluene or a plant recycled solvent. A suitable polymerization feed contains between 30 and 50 wt% and preferably between 35 and 45 wt% of polymerisable monomers so the ultimate yield per total feed will be between 30 and 50 wt%. The petroleum feed streams generally contain unsaturated hydrocarbons consisting of C5 and C6 olefins and/or diolefins boiling in the range from 20 to 100°C, preferably from 30 to 70°C. The cyclopentadiene and methylcyclopentadiene has generally been removed by heatsoaking the C5/C6 olefinic and diolefinic fraction at temperatures between 100 and 160°C and fractionation of the obtained dimers by distillation. It is however found that feedstocks containing cycloolefinic and cyclodiolefinic components like cyclopentadiene and dicyclopentadiene contribute to more cyclic and rigid structures in the resins which eventually results in a better adhesive performance in a hot melt pressure sensitive formulation (see example 3). Other cyclic dienes which are formed by co-dimerization of the cyclic dienes with C5 linear conjugated dienes or other reactive olefinic components in the petroleum feed stream, can also contribute to a higher degree of cyclic structures in the final resin. Average compositions of two used petroleum feed streams, with and without cyclodiolefins are given below. Feed Without With Cyclodiolefins A B Total olefins 13 11 Total cycloolefins 17 14 Total diolefins 65 55 Total cyclodiolefins <2 15 Examples of olefins are: isobutylene, 1-pentene, 2-methyl-1-pentene and trans and cis 2-pentene. Examples of cycloolefins are cyclopentene and cyclohexene. Examples of diolefins are cis and trans-piperylene (1,3-pentadiene), 1,4-pentadiene, isoprene, 1,3-hexadiene and 1,4-hexadiene. Examples for cyclodiolefins are cyclopentadiene, dicyclopentadiene, methyl and ethyl derivatives of both components and codimers of the cyclopentadiene and the diolefins. A commercial sample of a petroleum feed without any cyclodiolefins is Shell's (NL) super piperylene concentrate and a commercial sample of the preferred petroleum feed containing the desired cyclodiolefins is Shell's (NL) regular piperylene concentrate. The cyclodiolefinic components can of course also be added to a cyclodiolefinic poor stream. A particularly suitable petroleum stream contains at least 70 wt% of polymerisable monomers with at least 50 wt% piperylene. Further it contains less than 2 wt% isoprene. To obtain the lowest possible melt viscosity of the hot melt pressure sensitive adhesive composition it contains at least 10 wt% cyclopentene and at least 10 wt% and preferably at least 15 wt% of cyclodiolefinic components like cyclopentadiene and/or dicyclopentadiene. As chain transfer agent generally isobutylene, 2-methyl-1-butene, 2-methyl-2-butene or their dimeric oligomers are used to obtain resins with a lower and narrower molecular weight distribution. The components can be applied pure or diluted in an inert solvent like toluene or unreactive C4 to C6 components. An example for such a stream is isobutylene Raffinate 1 ex DSM. Isoamylene (2-methyl-2-butene) as chain transfer agent results a relatively R&B softening point at a similar molecular weight compared to other chain transfer agents. For cost price reasons it is preferred to use isobutylene pure or in a diluted form. Addition of more chain transfer agent decreases both, the R&B softening point and the molecular weight. The solvent used during the polymerization is pure toluene or plant recycled toluene. The plant recycled toluene is preferred because the use of plant toluene containing unreacted compounds originating from the petroleum feed stream, like cyclopentane, n-pentane, isopentane and cyclohexane, results in a higher R&B softening point at a similar molecular weight as compared to the use of pure toluene. The catalyst for the polymerization is used in an amount of 1.0 to 8.0 wt%, preferably 3.0 to 6.0 wt% and more preferably 4.0 to 5.0 wt% based on the amount of polymerisable components in the polymerization feed. It is found in this invention that a higher catalyst level, optionally in combination with a higher temperature, lowers the molecular weight while the resin softening point is kept constant. The resulting resin has a lower melt viscosity in a hot melt pressure sensitive composition. The increase of the catalyst level also increases the compatibility to aromatic solvents as reflected by a lower MMAP cloud point (see example 1). The catalyst can be chosen from any suitable Friedel-Crafts catalyst, such as aluminum trichloride, aluminum bromide, aluminum fluoride, titanium tri and tetrachloride, tin tetrachloride, boron trifluoride, or solutions, slurries or complexes thereof. Usually polymerization temperatures are between 0 and 100°C but preferred in this invention is the range from 50 to 120°C. It was found that a higher reaction temperature resulted in a more cyclic structure reflected by a lower molecular weight when the resin softening point is kept constant. Again the resulting resin caused a lower melt viscosity in the hot melt pressure sensitive composition together with excellent tack and shear properties (see example 2). The polymerization can be carried out in a continuous process or in a batch mode. The reaction time is typically from 1.0 to 4.0 hours and depends inter alia on the reaction temperature. After polymerization the residual catalyst may be removed by, for example, addition and extraction with water. The thus obtained polymer-solvent mixtures may be stripped to remove unreacted hydrocarbons, solvents and low molecular weight oligomers. The final resin usually has a higher softening point. Thus obtained resins which are most suitable for use as tackifiers according to this invention have: a) a R&B softening point varying from 75 to 110°C, preferably from 90 to 100°C. b) an Mn from 600 to 1300, preferably from 700 to 1000 Dalton, an Mw from 1000 to 2600, preferably below 2000 Dalton, a z-average molecular weight (Mz) from 1900 to 5000, preferably below 4000 Dalton and an Mw/Mn below 2.0. c) a level of aromatic protons below 1.5 % with respect to all protons determined by NMR. d) an MMAP cloud point of 90°C or less Especially the last statement is new for aliphatic resin based on petroleum feed streams. Normally the MMAP cloud point of commercially available non-modified aliphatic resins based on similar petroleum feed streams is 90°C or higher, whereas lower MMAP values could only be obtained with aromatic modified resins. This is illustrated in the following table: R&B (°C) Mz (Dalton) MMAP (°C) Remarks Escorez 2203 94 3200 88 Aromatic Modified Escorez 1310 94 3000 96 Aliphatic Resin Wingtack 95 99 2900 100 Aliphatic Resin Piccotac® 95E 95 3400 95 Aliphatic Resin Hercotac® 1148 96 4000 88 Aromatic Modified In contrast thereto, it was observed that due to the improved compatibility of the resins of the present invention, the MMAP cloud point decreased as a function of the amount of cyclic structures. A particular preferred tackifier for use in a hot melt pressure sensitive composition has the following typical properties (see also example 4) : R&B Softening point (°C) 96 MMAP (°C) 86 Aromatic protons (NMR) 0.7 Colour 50% in toluene (Gardner) 6 Mn (Dalton) 830 Mw (Dalton) 1460 Mz (Dalton) 2800 The control of the amount of cyclic structures can be carried out by varying the catalyst level and the reaction temperature. Furthermore, the desired R&B softening point which is also expected to depend on the amount of cyclic structures can be controlled by the amount of chain transfer agent. Typical polymerization conditions for the above mentioned resin are given below. Because the amount of cyclic components in the feed is also influencing the final amount of cyclic structures in the resin and thus the ultimate melt viscosity of a hot melt pressure sensitive composition, a preferred composition is given as well. The resins according to this invention can be blended with S-I-S polymers and additives to obtain a hot melt pressure sensitive adhesive composition having a low melt viscosity together with excellent tack and shear performance. Such a hot melt pressure sensitive adhesive composition can be used in a variety of forms. Particularly preferred application forms are adhesive tapes and labels. The hot melt pressure sensitive adhesive composition generally consists of an S-I-S block copolymer, a petroleum tackifier resin as described in this invention and other additives as known in the art like hydrocarbon extender oils, antioxidants, colorants, fillers etc. Suitable extender oils are selected from the group of aromatic oils, naphthenic oils, paraffinic oils or mixtures of those. The quantity of the petroleum resin used in combination with the block copolymer may range from 70 to 200 parts by weight per 100 parts of block copolymer. A more preferred range is from 90 to 150 parts by weight per 100 parts block copolymer. Where used, the amount of extender oil is added at a level up to 70 parts per weight per 100 parts block copolymer, more preferably in a range from 5 to 50 parts by weight. The S-I-S block copolymers can be selected from the group of polymers containing 0 to 30 parts per weight of styrene and 0 to 40 parts per weight of diblocks. Examples of such polymers are Kraton D 1107, Kraton D KX 601 Cs, Kraton D 1114 and Vector 4111. As mentioned earlier, a hot melt formulation according to this invention preferably exhibits a melt viscosity of below 100,000 mPas (CPS) measured at 175°C and more preferably lower than 60,000 mPas at 175°C. The most preferred melt viscosity at 175°C is in the range from 35,000 to 50,000 mPas. Because the decrease of the viscosity is not caused by adding aromatic monomers to the polymerization feed, the resin according to this invention has advantages over other well known resins used in this kind of application: 1. - Because of more cyclic structures, the resin has a lower melt viscosity than aliphatic resins like Piccotac 95E and Escorez 1310 in a comparable hot melt pressure sensitive composition. 2. - Because of more cyclic structures and hence a lower molecular weight of the resin, the hot melt composition containing the resin according to this invention has a rolling ball tack which is comparable to or even better than existing aliphatic or aromatic modified resins like Piccotac 95E or Escorez 2203 and Hercotac 1148. 3. - Because very little aromates are built in, resins made according to this invention give better high temperature shear strengths than aromatic modified resins like Escorez 2203, Hercotac 1148 and Hercules RESIN A. EXAMPLES Examples 1 to 4 illustrate the effects of the polymerization conditions on the resin properties. The advantages on the ultimate melt viscosity at 175°C are also demonstrated in a formulation with Kraton D 1107 and Shellflex FC 451 in a Polymer/Resin/Oil weight fraction of 100/120/20. The resin according to this invention which is used in the following examples will be hereinafter called: Inventive aliphatic hydrocarbon resin, or briefly: Inventive Resin. A typical composition of the used petroleum feed streams (with and without cyclodiolefins) and the plant recycled solvent is given below : Stream piperylene Regular piperylene Solvent Feed A B isobutylene * 0.0 0.0 0.0 n-pentane 0.2 0.0 1.5 isoprene * 0.5 0.5 0.0 trans-2-pentene 1.8 0.9 2.5 ois-2-pentene 3.0 1.9 2.2 isoamylene * 7.8 5.6 0.3 t-piperylene * 40.8 33.2 0.1 c-piperylene * 23.0 18.7 0.0 cyclopentene 16.6 13.4 6.7 cyclopentane 4.8 3.8 18.3 cyclopentadiene * 0.6 4.7 0.0 dicyclopentadiene * 0.0 9.4 0.0 other C5 + C6's 1.1 4.4 16.0 Toluene 0.0 0.0 2.4 monomers (*) 72.6 72.2 0.5 Not all mentioned resins in the examples were prepared using exactly the same above mentioned feed streams but these compositions are given because these results are typical and represent all other used petroleum feeds and solvents. The catalyst used in the examples was a 52 wt% AlCl 3 solution. The abbreviations and trade names used in the following are explained in the Experimental Section below. Feed A does not produce a resin in accordance with the present invention. Example 1 Table 1 shows the effect of using more catalyst for a feed with and a feed without cyclodiolefinic components on the final resin properties. Effect of catalyst level Feed A A B B Ex. No. 1a 1b 1c 1d Piperylene (A/B) 41.3 41.3 36.0 36.0 PR solvent 58.7 58.7 64.0 64.0 Catalyst 3.0 5.0 3.0 5.0 Temperature 55 55 45 45 Isobutylene 12 12 13 13 R&B 89.2 89.3 90.1 93.1 MMAP 94 92 90 88 Colour 3.6 4.7 5.2 6.1 Mn 728 689 920 871 Mw 1366 1235 1648 1444 Mz 2158 1941 3019 2525 Pd 1.88 1.79 1.79 1.66 Viscosity 52900 41500 52200 44200 Ball tack (cm) 1.2 2.0 1.6 2.4 PEEL to STEEL (N/25mm) 13.1 11.7 15.2 17.1 LOOP tack (N/25 mm) 25.4 21.4 28.8 26.4 SAFT (0.5 kg, °C) 97 95 94 93 Shear to carton (40°C, 1 kg, min) 1130 731 85 56 Shear to steel (40°C, 2.5 kg, min) 38 52 98 37 Shear to steel (70°C, 0.5 kg, min) 744 584 960 876 The results clearly show that due to a higher catalyst level the MMAP and the molecular weight decrease while the R&B softening points remain almost the same or show a slight increase. The viscosity drastically decreases when more catalyst is used. Example 2 Table 2 shows the effect of using higher reaction temperatures for a feed with and a feed without cyclodiolefinic components on the final resin properties. Effect of temperature Feed A A B B Ex.No. 2a 2b 2c 2d Piperylene (A/B) 41.3 41.3 36.0 36.0 PR solvent 58.7 58.7 64.0 64.0 Catalyst 5.0 5.0 3.0 3.0 Temperature 15 55 45 65 Isobutylene 12 12 13 13 R&B 83.3 89.3 90.1 92.0 MMAP 93 92 90 89 Colour 2.4 4.7 5.2 6.2 Mn 975 689 920 801 Mw 1501 1235 1648 1417 Mz 2402 1941 3019 2636 Pd 1.54 1.79 1.79 1.77 Viscosity 50700 41500 52200 41200 Ball tack (cm) 1.0 2.0 1.6 1.6 PEEL to STEEL (N/25mm) 11.9 11.7 15.2 14.1 LOOP tack (N/25 mm) 26.3 21.4 28.8 28.3 SAFT (0.5 kg, °C) 96 95 94 93 Shear to carton (40°C, 1 kg, min) 856 731 85 32 Shear to steel (40°C, 2.5 kg, min) 37 52 98 140 Shear to steel (70°C, 0.5 kg, min) 597 584 960 952 The results clearly show that due to a higher temperature the MMAP and the molecular weight decrease slightly while the R&B softening point shows an increase. Using higher temperatures, the melt viscosity decreases drastically. When the temperature is increased from 60 to 80 and 100°C the same trends for the resin properties were observed. The results are given in the table below. Effect of temperature Feed B B B Ex. No. 2e 2f 2g Piperylene (B) 40.0 40.0 40.0 PR solvent 60.0 60.0 60.0 Catalyst 3.6 3.6 3.6 Temperature 60 80 100 Isobutylene 8.0 8.0 8.0 R&B 94.1 99.6 101.5 MMAP 85 82 78 Colour 5.5 6.9 8.7 Mn 874 828 765 Mw 1393 1374 1394 Mz 2490 2751 3368 Pd 1.59 1.66 1.82 Viscosity (mPas) 42800 37100 29500 Ball tack (cm) 1.4 2.0 2.0 PEEL to STEEL (N/25mm) 14.8 17.0 15.6 LOOP tack (N/25mm) 24.6 27.7 24.9 SAFT (0.5 kg, °C) 94 96 96 Shear to carton (40°C, 1kg, min) 27 51 29 Shear to steel (40°C, 2.5kg, min) 158 157 173 Shear to steel (70°C, 0.5kg, min) 890 1038 1380 Example 3 Table 4 illustrates the advantage of using a feed containing more cycloolefins and cyclodiolefins. For the example resins were chosen having a similar R&B softening point and molecular weight. Effects of the feed composition. Feed A B A B Ex. No. 3a 3b 3c 3d Piperylene (A/B) 41.3 36.0 41.3 36.0 PR solvent 58.7 64.0 58.7 64.0 Catalyst 3.0 3.0 4.0 3.75 Temperature 55 65 35 50 Isobutylene 4.0 7.0 8.0 10.0 R&B 104.5 104.9 95.1 96.1 MMAP 95 89 94 87 Colour 2.9 5.7 2.7 5.6 Mn 1146 928 1075 837 Mw 2076 1906 1759 1548 Mz 4024 4207 3023 3042 Pd 1.81 2.05 1.64 1.85 Viscosity 76000 50000 68200 37900 Ball tack (cm) 1.7 3.8 2.2 3.0 PEEL to STEEL (N/25mm) 16.1 19.0 15.3 20.7 LOOP tack (N/25 mm) 27.0 31.4 27.5 32.8 SAFT (0.5 kg, °C) 98 95 101 93 Shear to carton (40°C, 1 kg, min) 1321 149 511 232 Shear to steel (40°C, 2.5 kg, min) 303 288 89 120 Shear to steel (70°C, 0.5 kg, min) 1180 1056 1014 809 The examples clearly show that resins with similar R&B softening points and molecular weights are different with respect to the MMAP and the melt viscosity of the hot melt pressure sensitive composition. The presence of the cyclodiolefins, like cyclopentadiene and dicyclopentadiene contribute already for a great part to the cyclic character of the resin and cause a lower melt viscosity of the hot melt formulation and a lower MMAP of the resin. Generally it is seen that in case of the presence of cyclic diolefins more catalyst or a higher temperature and more chain transfer agent is necessary to obtain a similar R&B and molecular weight. The use of a feed containing the cycloolefins and cyclodiolefins seems to broaden the molecular weight distribution slightly. Example 4 The resins in table 5 are examples of resins with the most preferred properties for use as tackifiers in hot melt adhesive compositions. Optimal resins based on both feeds Feed A B B B PP 4a 4b 4c 4d Piperylene (A/B) 41.3 36.0 40.0 36.0 PR solvent 58.7 64.0 60.0 64.0 Catalyst 4.0 4.0 4.0 3.75 Temperature 70 55 55 50 Isobutylene 6.0 10.0 9.0 10.0 R&B 98.0 97.1 96.5 96.1 MMAP 93 87 86 87 Colour 4.5 6.1 5.9 5.6 Mn 901 802 827 837 Mw 1470 1436 1459 1548 Mz 2596 2595 2806 3042 Pd 1.63 1.79 1.76 1.85 Viscosity 49200 43000 -- 37900 Ball tack (cm) 2.6 3.2 -- 3.0 PEEL to STEEL (N/25mm) 14.5 17.3 -- 20.7 LOOP tack (N/25 mm) 19.1 34.0 -- 32.8 SAFT (0.5 kg, °C) 102 95 -- 93 Shear to carton (40°C, 1 kg, min) 337 155 -- 232 Shear to steel (40°C, 2.5 kg, min) 73 168 -- 120 Shear to steel (70°C, 0.5 kg, min) 1446 1309 -- 809 Especially 4b, 4c and 4d are good examples of resins made according to this invention. All three resins are within the scope of this invention as defined by the appending claims and all are based on a feed containing cyclodiolefinic components. The resins of example 4b and 4d show good ball tack and sufficiently high shear strengths. Example 5 To determine whether the MMAP decrease was caused by the incorporation of toluene from the process solvent or by the cyclization reaction, IR and NMR analyses were conducted to determine the amount of aromatic protons present in the resin. NMR results of several samples Resin 6.5-7.5 ppm 4.7-5.4 ppm 0.5-3 ppm RESIN B 7.84 5.00 87.15 RESIN C 2.58 2.87 94.55 INVENTIVE RESIN 0.69 2.76 96.55 HERCURES® C 0.87 4.15 94.98 PICCOTAC® 95E 0.59 3.37 96.04 The table shows the percentages of aromatic protons (between 6.5 and 7.5 ppm) compared to the percentage of =CH 2 -like protons (4.7 to 5.4 ppm) and aliphatic protons (0.5 to 3.0 ppm). It is clearly shown that the amount of protons in the aromatic range for the Inventive Resin is comparable to other aliphatic resins like Hercures® C and Piccotac® 95E. The latter two resins have an MMAP of 93 - 95°C while the Inventive Resin has an MMAP of 86°C. RESIN C, which is a 5 wt% per resin aromatic modified aliphatic resin having an MMAP of 85°C, showed a significantly higher amount of aromatic protons. A higher aromatic modified resin (RESIN B, about 18 wt% per resin aromatic modified) showed a higher amount of aromatic protons. Example 6 Table 7 shows the results of several resins in a hot melt pressure sensitive adhesive composition in comparison to each other. HM PSA performance in Kraton D 1107 Ex. No. 6a 6b 6c 6d Kraton D 1107 100 100 100 100 INVENTIVE RESIN 120 RESIN B 120 PICCOTAC® 95E 120 HERCOTAC® 1148 120 Shellflex 451 FC 20 20 20 20 Irganox 1010 2 2 2 2 Viscosity at 175°C(mPas) 37900 58800 59500 45500 Ball tack (cm) 3.0 7.0 3.6 5.7 PEEL to STEEL (N/25mm) 20.7 17.1 16.9 19.9 LOOP tack (N/25 mm) 32.8 29.0 30.5 30.8 SAFT (0.5 kg, °C) 93 93 96 97 Shear to carton (40°C, 1 kg, min) 232 391 723 620 Shear to steel (40°C, 2.5 kg, min) 120 353 201 121 Shear to steel (70°C, 0.5 kg, min) 809 310 1326 691 The results clearly show that the melt viscosity and the rolling ball tack using the resin of the present invention, is the best of all the tested resins. The shear to carton at 40°C is not significantly different for the four resins. The shear to steel at 70°C for the Inventive Resin is better for using Hercotac 1148 and Hercules RESIN B (about 18 wt% per resin aromatic modified aliphatic resin). The use of Piccotac 95E ( aliphatic resin) results in a better high temperature shear to steel but also in a higher viscosity. The Inventive Resin was also compared with some competitive resin samples. Tested were Escorez 1310 LC, an aliphatic resin like Piccotac 95E, and Escorez 2203 LC, a slightly aromatic modified resin comparable to Hercotac 1148. Further Hercules RESIN A was compared as well. Hercules RESIN A is like Hercules RESIN B a more aromatic modified resin than Escorez 2203 and Hercotac 1148. HM PSA performance in Kraton D 1107 Ex. No. 6a 6b 6c 6d Kraton D 1107 100 100 100 100 INVENTIVE RESIN 120 Escorez 1310 LC 120 Escorez 2203 LC 120 RESIN A 120 Shellflex 451 FC 20 20 20 20 Irganox 1010 2 2 2 2 Viscosity at 175°C (mPas) 37900 85400 45000 40000 Ball tack (cm) 3.0 2.6 3.8 6.6 PEEL to STEEL (N/25mm) 20.7 14.5 17.8 18.1 LOOP tack (N/25 mm) 32.8 19.1 30.7 25.7 SAFT (0.5 kg, °C) 93 102 95 85 Shear to carton (40°C, 1 kg, min) 232 337 242 383 Shear to steel (40°C, 2.5 kg, min) 120 73 134 177 Shear to steel (70°C, 0.5 kg, min) 809 1446 781 102 The results clearly show again that the melt viscosity and the rolling ball tack using the Inventive Resin are comparable to a slightly aromatic modified resin like Escorez 2203 LC. The rolling ball tack using Hercules RESIN A was found to be higher due to the higher molecular weight. The hot melt viscosity using Escorez 1310 LC is higher than observed for Piccotac 95E and especially the Inventive Resin. The shear to steel at 70°C using the Inventive Resin was found to be better than for the Hercules RESIN A. The use of Escorez 1310 LC gives a better high temperature shear to steel like found for Piccotac 95E but also gives the highest viscosity. Example 7 The inventive aliphatic hydrocarbon resin was also evaluated in other S-I-S polymers in the same Polymer/ Resin/Oil ratio. HM PSA performance in compositions with different polymers Ex. No. 7a 7b 7c 7d Kraton D 1107 100 Kraton D KX-601-CS 100 Kraton D 1114-X 100 Vector 4111 100 INVENTIVE RESIN 120 120 120 120 Shellflex 451 FC 20 20 20 20 Irganox 1010 2 2 2 2 Viscosity at 175°C (mPas) 37900 48200 37800 47200 Ball tack (cm) 3.0 1.6 1.8 1.6 PEEL to STEEL (N/25mm) 20.7 15.6 14.7 14.3 LOOP tack (N/25 mm) 32.8 27.2 24.6 26.3 SAFT (0.5 kg, °C) 93 95 101 100 Shear to carton (40°C, 1 kg, min) 232 980 1204 924 Shear to steel (40°C, 2.5 kg, min) 120 63 325 175 Shear to steel (70°C, 0.5 kg, min) 809 1647 5210 3604 The results clearly show that the use of the aliphatic resin of the present invention results in a low hot melt viscosity together with good balanced tack and shear properties in all four polymers. Example 8 In table 10 some results are given varying the resin and oil amounts in the adhesive formulation. Vector 4111 was used as polymer. HM PSA performance for several formulations Ex. No. 8a 8b 8c 8d Vector 4111 100 100 100 100 Vector 4111 (wt%) 42 45 45 36 INVENTIVE RESIN 120 118.6 98.5 148.6 INVENTIVE RESIN(wt%) 50 53 44 53 Shellflex 451 FC 20 5.2 25.4 37.8 Shellflex 451 FC (wt%) 8 2 11 11 Irganox 1010 2 2 2 2 Viscosity at 175°C (mPas) 51600 121200 63500 21800 Ball tack (cm) 2.6 3.0 1.0 1.0 PEEL to STEEL (N/25mm) 16.7 17.0 13.5 19.3 LOOP tack (N/25 mm) 35.6 31.1 27.7 38.1 SAFT (0.5 kg, °C) 103 111 101 101 Shear to carton (40°C, 1 kg, min) 409 351 89 60 Shear to steel (40°C, 2.5 kg, min) 639 1342 298 574 Shear to steel (70°C, 0.5 kg, min) 2718 14000 835 900 The above formulations indicate that the amounts of polymer, resin and oil can be varied to control the hot melt viscosity while tack and shear properties still remain sufficient. Examples 1 a, 1b, 2a, 2b, 3a, 3c, 4a and 8b are incorporated herein by way of comparative examples. EXPERIMENTAL SECTION - MATERIALS & METHODS ABBREVIATIONS In the above text and tables, the following abbreviations were used: PR solvent Solvent used for the Polymerisation Reaction R&B Ring and Ball softening point (measured as described below) MMAP Mixed Methylcyclohexane Aniline Cloud Point (measured as described below) Mn Number average molecular weight Mw Weight average molecular weight Mz z-average molecular weight Pd Polydispersity (=Mw/Mn) AH formulation Number of the hot melt adhesive HM PSA Hot Melt Pressure Sensitive Adhesive SAFT Shear Adhesion Failure Temperature METHODS Method for the preparation of the resins: All resins mentioned herein were prepared in a continuous process, but a batch production would also be possible. The resin feed was dried over a calciumchloride and a molecular sieve drier and added together with the chain transfer agent with a rate of 1500 ml/h to a continuously stirred tank reactor of 6 liter capacity. The catalyst was simultaneously added and the mixture was circulated from the bottom of the reactor to the catalyst inlet point. The mixture was continuously removed at a level of 3 liters so that the reaction time for all experiments was 2 hours. The mixture was deactivated with water and washed in three steps with water before it was stripped under vacuum and with steam to remove the solvent and all the low molecular weight materials. Method for the determination of the R&B softening point: The R&B (Ring and Ball) softening point was determined according to ASTM D-36-70 with the Walter Herzog R&B apparatus, model MC-735. Method for the determination of the MMAP: The MMAP (Mixed Methylcyclohexane Aniline Cloud point) was determined using a modified ASTM D-611-82 procedure. The Methylcyclohexane is substituted for the heptane used in the standard test procedure. The procedure uses resin/aniline/methylcyclohexane in a ratio 1/2/1 (5 g/10 ml/5 ml), and the cloud point is determined by cooling a heated, clear blend of the three components until a complete turbidity just occurs. Method for the determination of the resin colour: To determine the Gardner colour the resin was mixed with reagent grade toluene at room temperature until all the resin was dissolved. The colour was determined spectrophotometrically using the Dr. Lange LICO 200 apparatus. Method for the determination of the molecular weights: The molecular weights Mn, Mw, Mz and the polydispersity (=Mw/Mn) were determined by size exclusion chromatography using a refractive index detector. Method for the determination of the NMR spectra: The NMR spectra of the resin were determined in CDCl 3 as solvent. Method for the determination of the viscosity: The hot melt viscosity was determined using a brookfield viscosity meter at 175°C by ASTM D-3236. Method for the determination of the peel strength: The peel strength is measured by a PSTC-1 test. Method for the determination of the ball tack: The ball tack is measured by a PSTC-6 test. Method for the determination of the Loop tack: The loop tack is measured by a FINAT-9 test. Method for the determination of the shear strength: The shear strengths were measured by a PSTC-7 test. Method for the determination of the SAFT: The Shear adhesion failure temperature (SAFT) was determined according to the Hercules test method WI 20/1/W126. MATERIALS Materials used in preparing the adhesive compositions as mentioned in the examples are as follows: Shellflex 451 FC - A paraffinic extender oil available from Shell. KRATON D 1107 - A polystyrene-polyisoprene-polystyrene (S-I-S) triblock copolymer of Shell Chemical having a styrene content of 15 wt%, a diblock content of 19 wt%, a melt flow rate of 9 g/10min and a weight average molecular weight of 205,000 Dalton. KRATON D KX-601-CS - A polystyrene-polyisoprene-polystyrene (S-I-S) triblock copolymer of Shell Chemical having a styrene content of 15 wt%, a diblock content of 19 wt%, a melt flow rate of 9 g/10min and a weight average molecular weight of 205,000 Dalton. KRATON D 1114-X - A linear polystyrene-polyisoprene-polystyrene triblock copolymer supplied by Shell Chemical having a styrene content of 19.0 wt%, a melt flow rate of 11 g/10min, a weight average molecular weight of about 160,000 and 0 wt% diblocks (SI). Vector 4111 S-I-S - A linear polystyrene-polyisoprene-polystyrene triblock copolymer supplied by Dexco Polymers having a styrene content of 19.0 wt%, a melt flow rate of 11 g/10min, a weight average molecular weight of about 170,000, and 0 wt% diblocks (SI). Hercules Hercotac 1148 hydrocarbon resin - A petroleum resin available from Hercules containing about 5 to 10 wt% of a polymerized aromatic monomer and having a softening point of about 95°C. Hercules Piccotac x95E hydrocarbon resin - A petroleum resin without any polymerized aromatic components having a softening point of about 95°C and number average molecular weight of about 1100 Dalton. Escorez 1310 LC - A petroleum resin available from Exxon containing about 0.3% by weight of polymerized styrene and having a softening point of about 93.5°C. Escorez 2203 LC - A petroleum resin available from Exxon containing about 8 to 10 wt% of polymerized styrene and having a softening point of about 92°C and a number average molecular weight of about 1150. Winptack 95 - A petroleum resin available from Good Year like Piccotac 95E and Escorez 1310 having a softening point of about 96°C and a number average molecular weight of about 1100. Hercules RESIN A hydrocarbon resin - A petroleum resin available from Hercules containing about 10 to 25 wt% of some polymerized aromatic monomers and having a softening point of about 95°C. Hercules RESIN B hydrocarbon resin - A petroleum resin available from Hercules containing about 10 to 25 wt% of a polymerized aromatic monomer and having a softening point of about 92°C and a colour of about 3 Gardner. Hercules RESIN C hydrocarbon resin - A petroleum resin available from Hercules containing about 3 to 10 wt% of a polymerized aromatic monomer and having a softening point of about 94°C. Irganox 1010 - an antioxidant containing mainly pentaerythrityl-tetrakis[3-(3,5-di-tert.butyl-4-hydroxyphenyl)-propionate as commercial sample from Ciba-Geigy.

Claims: A petroleum-based aliphatic resin having a) a Ring and Ball (R&B) softening point in the range of 75 to 110°C, b) a weight average molecular weight (Mw) of 1000 to 2600 Dalton, a z-average molecular weight (Mz) from 1900 to 5000 Dalton and an Mw/Mn below 2.0, c) a level of aromatic protons below 1.5 % with respect to all protons determined by 1 H-NMR, and d) a mixed methylcyclohexane aniline cloud point (MMAP) of 90°C or less. The resin according to claim 1 wherein the R&B softening point is between 90 and 100°C. The resin according to claims 1 or 2 which has an Mw below 2000 Dalton, an Mz below 4000 Dalton and an Mw/Mn below 2.0. Use of a resin according to any of claims 1 to 3 for the preparation of a hot melt pressure sensitive adhesive composition. Use of a resin according to any of claims 1 to 3 as a raw material for a hydrogenation, hydrotreatment and/or quenching process to improve the resin colour. A hot melt pressure sensitive adhesive composition which includes a petroleum-based resin according to claims 1 to 3 and a polymer. A hot melt pressure sensitive adhesive composition according to claim 6 wherein said polymer is selected from a styrene-isoprene-styrene (S-I-S) polymer. A hot melt pressure sensitive adhesive composition according to claim 7 wherein the polymer is an S-I-S block copolymer containing 10 to 30 parts by weight of styrene. A hot melt pressure sensitive adhesive composition according to claims 6 to 8 which further includes an extender oil. A hot melt pressure sensitive adhesive composition according to claims 6 to 8 which contains 70 - 200 parts by weight of a petroleum-based aliphatic resin, 100 parts by weight of a polymer and 0 - 70 parts by weight of an extender oil. A hot melt pressure sensitive adhesive composition according to claims 6 to 9 which contains 90 - 150 parts by weight of a petroleum-based aliphatic resin, 100 parts by weight of a polymer and 5 to 50 parts by weight of an extender oil. A hot melt pressure sensitive adhesive composition comprising a) 100 parts by weight of a Styrene-Isoprene-Styrene (S-I-S) rubber b) 70 - 200 parts by weight of a petroleum-based aliphatic resin having a Ring and Ball (R&B) softening point in the range of 75 to 110°C a weight average molecular weight (Mw) of 1000 to 2600 Dalton, a z-average molecular weight (Mz) from 1900 to 5000 Dalton and an Mw/Mn below 2.0 a level of aromatic protons below 1.5 % with respect to the total protons determined by 1 H-NMR and a mixed methylcyclohexane aniline cloud point (MMAP) of 90°C or less, c) 0 - 70 parts by weight of an extender oil, characterized in that the composition has a viscosity of 100,000 mPas or less, measured according to ASTM method D3236 at 175°C with a Brookfield viscosity meter. A hot melt pressure sensitive adhesive composition according to claim 12 which has a viscosity of 80,000 mPas or less at 175°C. A hot melt pressure sensitive adhesive composition according to claim 13 which has a viscosity of 35,000 to 50,000 mPas at 175°C. The use of a hot melt pressure sensitive adhesive composition as defined in any of claims 6 to 14 for preparing an adhesive tape or an adhesive label.

Inventors: DONKER CHRETIEN P L C, LENSELINK BERT, THEELEN MICHEL HENDRIKUS, DONKER, CHRETIEN P.L.C., LENSELINK, BERT, THEELEN, MICHEL HENDRIKUS
Applicants: EASTMAN CHEMICAL RESINS INC, EASTMAN CHEMICAL RESINS, INC.
Application year: 1996
Main classification: C08F240
IPC codes: C09J125, C09J11, C09J201, C09J153, C08F8, G09F3, C08F240, C09J157, C09J7, C09J131