AMORPHOUS POLY-ALPHA-OLEFINS AND USE THEREOF IN HOT-MELT COMPOSITIONS HAVING IMPROVED SPRAYABILITY

Abstract

The invention relates to amorphous poly-alpha-olefins, which are characterized in that said amorphous poly-alpha-olefins have a viscosity at 190° C. of less than 5000 mPas, a molar mass distribution (Mw/Mn) of 3 to 8, a quotient Mz/Mw of less than or equal to 3.0 and a quotient Mz/Mn of less than 21.0. The invention further relates to a method for producing degraded amorphous poly-alpha-olefins, in particular the amorphous poly-alpha-olefins according to the invention, and to the use of the amorphous polyalpha-olefins according to the invention or produced according to the invention in hot-melt adhesive compositions.

Claims

1. An amorphous poly-alpha-olefin, wherein it has a viscosity at 190° C. of less than 5000 mPas, a molecular weight distribution (Mw/Mn) of 3 to 8, a quotient of Mz/Mw of not more than 3.0, and a quotient of Mz/Mn of less than 21.0, in each case determined by the method specified in the description.

2. An amorphous poly-alpha-olefin, wherein it includes from 0.01% to 3% by weight of at least one antioxidant.

3. An amorphous poly-alpha-olefin, wherein it includes from 0.01% to 3% by weight of at least one degradation product of a free-radical initiator.

4. A process for producing a degraded amorphous poly-alpha-olefin, wherein an amorphous poly-alpha-olefin having a viscosity at 190° C. of not less than 5000 mPas, is subjected to a free-radical, preferably peroxidic, degradation, the degradation reaction being conducted over a period of 15 seconds to 1200 seconds.

5. The process according to claim 4, wherein the free-radical degradation is conducted in an extruder.

6. The process according to claim 4, wherein the free-radical degradation is conducted in the presence of a free-radical former.

7. The process according to claim 6, wherein the proportion of the free-radical formers used is from 0.01% to 10% by weight, based on the sum total of APAO and free-radical formers.

8. The process according to claim 4, wherein the degradation reaction is conducted at a temperature of 100 to 350° C.

9. The process according to claim 4, wherein the degradation reaction is conducted over a period of 30 seconds to 600 seconds.

10. The process according to claim 4, wherein the degradation reaction is conducted over a period of 15 seconds to 1200 seconds, and at a temperature T of 100 to 350° C., where the proportion A of free-radical formers used is from 0.01% to 10% by weight, based on the sum total of APAO and free-radical formers, wherein the product of t×T×A is from 500 to 1 000 000 [sec ° C. % by wt.], preferably from 1000 to 100 000 [sec ° C. % by wt.].

11. The process according to claim 4, wherein the reaction is conducted in a mixing unit.

12. The process according to claim 4, wherein an APAO is prepared.

13. A hot melt adhesive composition comprising the he use APAO according to claim 1.

14. The hot melt adhesive composition according to claim 13, wherein the composition at least 70% by weight, of amorphous poly-alpha-olefins.

15. The hot melt adhesive composition according to claim 13, wherein the melt-applied adhesive composition is applied by application by means of a spray nozzle, slot die, melt-applied adhesive gun or by melt casting, preferably by means of a spray nozzle, more preferably by means of spiral nozzles.

16. The hot melt adhesive composition according to claim 13, wherein the melt-applied adhesive composition is used in the applications of packaging, preferably cardboard packaging or paper, building, especially timber-frame construction, carpet, woodworking, preferably profile sealing and edge gluing, automobile, preferably roofs, air filters or vehicle lamps, mattresses, bitumen, hygiene articles, preferably diapers or napkins.

17. The amorphous poly-alpha-olefin of claim 1 wherein amorphous poly-alpha-olefin it has a viscosity at 190° C. of from 1000 to 4000 mPas, a quotient of Mz/Mw of from 1.1 to 2.9, and a quotient of Mz/Mn of from 9.1 to 19.9, in each case determined by the method specified in the description.

18. The process according to claim 4 wherein an amorphous poly-alpha-olefin having a viscosity at 190° C. of from 6000 to 100 000 mPas is subjected to a free-radical, preferably peroxidic, degradation, the degradation reaction being conducted over a period of 15 seconds to 1200 seconds.

19. The process according to claim 4 wherein an amorphous poly-alpha-olefin having a viscosity at 190° C. of from 7500 to 75 000 mPas is subjected to a free-radical, preferably peroxidic, degradation, the degradation reaction being conducted over a period of 15 seconds to 1200 seconds.

20. The process according to claim 4, wherein the free-radical degradation is conducted in the presence of a free-radical former selected from the group consisting of dibenzoyl peroxide, tert-butyl peroxyisopropylcarbonate, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, di-tert-butyl peroxide and p-methane hydroperoxide.

Description

[0047] The subject-matter of the present invention is more particularly elucidated by FIG. 1 to FIG. 3, without any intention that the subject-matter of the present invention be restricted thereto.

[0048] FIG. 1 is a schematic representation of an apparatus with which the APAOs degraded used in accordance with the invention can be produced. The apparatus has at least one mixing apparatus M, a feed for pre-radical former R, a feed for APAO to be degraded A, optionally a means of applying a vacuum V. The product that leaves the mixing apparatus M as product is degraded APAO Ad.

[0049] FIG. 2a shows an example of a nice spray pattern. It is clearly apparent that the pattern is regular and the filaments do not have any holes or drips.

[0050] FIG. 2b shows an example of a poor spray pattern. It is clearly apparent that the pattern is irregular and the filaments have holes or drips.

[0051] FIG. 3a depicts spraying onto a roll. From this viewing angle, it is very readily possible to determine the deflection of the spray filaments in and counter to coating direction.

[0052] FIG. 3b is a schematic diagram of the spray application of the adhesive from nozzle D onto a nonwoven V1. AR denotes the application direction or advance of the nonwoven V1. A further nonwoven V2 is applied to the adhesive applied.

[0053] FIG. 4a depicts the spray template for quantification of the deflection, on which an application has been made. The template is a coated and counter-laminated substrate (polypropylene/polypropylene). The deflections of 0 cm, 0.5 cm, 1 cm, 2 cm and 3 cm correspond to classes 0, 0.5, 1, 2 and >2.

[0054] FIG. 4b is a schematic diagram of the spray template for quantification of the deflection.

[0055] The subject-matter of the present invention is elucidated in detail in the examples which follow, without any intention that the subject-matter of the present invention be restricted to these.

EXAMPLES

Example 1: Production of Degraded APAO in a Reactor with Stirrer

[0056] 400 g of VESTOPLAST® 750, Evonik Resource Efficiency GmbH, are introduced into a laboratory pressure reactor with stirrer and heated up to 170° C. Once the temperature has been attained, 4% by weight (16 g) of the peroxide (Peroxan HX [2,5-dimethyl-2,5-di(tert-butylperoxy)hexane] from Pergan GmbH) is added and the mixture is stirred for 5 minutes. Subsequently, the mixture is discharged and the melt viscosity is determined at 190° C. on a Brookfield laboratory viscometer (see above for methods of determination). The viscosity of the mixture discharged at 190° C. was 4000 mPa*s. Determination of the viscosity at 190° C. of the VESTOPLAST® 750 used gave a value of −50 000 mPa*s. GPC analysis gave the following values: Mz: 145100 [g/mol]; Mw: 60390 [g/mol]; Mn: 14180 [g/mol]; Mw/Mn: 4.3; Mz/Mw: 2.4; Mz/Mn: 10.2.

[0057] In the same way, first degradation experiments were conducted with a low-viscosity base polymer B1 (VESTOPLAST® EP V2094, off-spec, viscosity at 190° C.=7700 mPa*s) with different amounts of the peroxide and at different reaction temperatures. Table B shows the experimental parameters used and the properties measured. The properties of non-degraded VESTOPLAST® 408 (identified in the table as B2) and VESTOPLAST® 750 (identified in the table as B3) are for comparison.

TABLE-US-00003 TABLE B Products used in Example 1, experimental parameters and product properties ascertained Base polymer B1 B1 B1 B1 B1 B2 B3 Viscosity [mPa*s] 7700 5302 3636 4500 2761 8200 52500 Peroxide [% by wt.] 0 0.5 1.5 0.5 1.5 0 0 Temperature [° C.] 0 130 130 170 170 0 0 Mn 12700 10950 11350 10480 8350 12000 17890 Mw 74950 75800 69900 65450 57250 82800 149810 Mz 275500 312500 249500 198000 151500 388000 564600 Mw/Mn 5.9 6.9 6.2 6.2 6.9 6.9 8.4 Mz/Mw 3.7 4.1 3.6 3.0 2.6 4.7 3.8 Mz/Mn 21.7 28.5 22.0 18.9 18.1 32.3 31.6

[0058] As can be inferred from Table B, by degradation of amorphous poly-alpha-olefin having a viscosity at 190° C. of not less than 5000 mPa s by means of free-radical degradation, APAOs having the desired material/product properties are obtainable.

Example 2: Production of Degraded APAO on the Pilot Plant Scale in an Extruder

[0059] An initial charge of 20 kg of VESTOPLAST® 750 in the form of pellets was conveyed through a feed into a Bersdorf DSK42 extruder. At the same time, 1.8 kg/h of VESTOPLAST® 750 and about 200 g/h of a 50% by weight Peroxan PK295V [1,1-di-(tert-butylperoxy)-3,3,5-trimethylcyclohexane] from Pergan GmbH (mixture in isododecane) were metered in. The dwell time (reaction time) of the reaction mixture in the extruder is 30 seconds and the temperature in the extruder is 160° C. The viscosity of the mixture discharged at 190° C. was 2800 mPa*s. Mz: 149200 [g/mol]; Mw: 61110 [g/mol]; Mn: 14350 [g/mol]; Mw/Mn: 4.3; Mz/Mw: 2.4; Mz/Mn: 10.4.

Example 3: Production of Melt-Applied Adhesive Compositions

[0060] The polymers obtained in Example 2 were processed to give a melt-applied adhesive composition. For this purpose, the components specified in Table C below were mixed with one another at 190° C. by stirring.

TABLE-US-00004 TABLE C Components used and, in brackets, % by mass of the components used for production of the melt-applied adhesive compositions Example APAO Tackifier resin Wax 3a From Example 2 (65)  Escorez ™ 5380 (30) Sarawax SX80 (5) 3b From Example 2 (100) 3c From Example 2 (70)  Escorez ™ 5300 (30)

Example 4: Verification of Sprayability

[0061] For the verification of sprayability, test series were conducted with 14 experiments for each melt-applied adhesive formulation at three temperatures for examination (120° C., 140° C. and 160° C.). At the same time, parameters such as air pressure at the nozzle and mass of the melt-applied adhesive applied were varied, taking account of the application window of the nozzle used. The experiments were conducted with a Meltex Hot Melt Coater spraying system from Nordson (model designation: MX 3012-1/0220-2086). The nozzle used was a Low Flow Signature Nozzle from Nordson. The hotmelt formulation to be sprayed is melted in the tank at 190° C. and conveyed by means of a pump to the nozzle, where, using an air stream applied, the hotmelt formulation is deposited by means of a heated air stream at the nozzle exit onto the nonwoven substrate running past beneath the nozzle. A video recording for 10 seconds was made of each experiment. The experimental parameters varied can be found in Table 1. [0062] Mass of the melt-applied adhesive applied: 0.5 to 10 g/m.sup.2 [depending on pump speed and belt speed] [0063] Speed of the substrate: 15 m/min [0064] Pressure/air rate at the nozzle: 10 to 1301 (STP)/min per nozzle/1 to 4 bar

TABLE-US-00005 TABLE 1 Experimental parameters used Parameter Abbreviation Unit Values Temperature T_nozzle ° C. 120 140 160 of the melt-applied adhesive Air pressure P bar 1 2 2.5 3 3.5 4 at the nozzle Pump speed rpm_pump % 13 26 35 73 93 (digital display) Distance d cm 4 of the nozzle from the substrate Nozzle type Nozzle — low flow signature nozzle

Assessment of the Spray Patterns

[0065] The spray patterns were assessed using the criteria described below. The results of the assessments are reported in Tables 2a to 2c.

Visual Impression of the Spray Pattern:

[0066] The visual impression of the spray pattern is to be assessed. This is a subjective assessment.

[0067] In the case of a good spray pattern, the melt-applied adhesive constructs fine threads that exactly cover the region beneath the nozzle. No threads run to the left or right and the surface is covered with a regular pattern. FIG. 2a shows an example of a nice spray pattern.

[0068] In the case of a poor spray pattern, the melt-applied adhesive has been applied to the substrate in thick lines and/or dots. The filaments are broader than the nozzle and irregular. There may be large holes in the spray pattern, and parts of the substrate may not be covered with melt-applied adhesive. FIG. 2b shows an example of a poor spray pattern.

Assessment:

[0069] 0=nice spray pattern [0070] 1=poor spray pattern

Edge Stability:

[0071] Edge stability relates to the stability of a straight line. Many holes in the line is a sign that the spray pattern does not have good edge stability. Individual outliers are neglected.

Assessment:

[0072] 0=edge stability [0073] 1=no edge stability
Deflection of the Filaments (from the Template Mask):

[0074] The deflection relates to the areas of the spray pattern in which the threads lie outside the central marking of 2.5 cm (the deflection is determined only for the threads visible against the dark template mask).

Assessment:

[0075] 0=no deflection [0076] 0.5=deflection of length up to 0.5 cm [0077] 1=deflection of length up to 1 cm [0078] 2=deflection of length up to 2 cm [0079] 3=deflection greater than a length of 2 cm

Fine Filaments:

[0080] The deflection relates to the areas of the spray pattern in which very fine filaments lie outside the central marking of 2.5 cm (the fine filaments are virtually invisible against the dark template mask and can only be seen when the template mask is held against the light).

Assessment:

[0081] 0=no deflection [0082] 0.5=deflection of length up to 0.5 cm [0083] 1=deflection of length up to 1 cm [0084] 2=deflection of length up to 2 cm [0085] 3=deflection greater than a length of 2 cm

Evaluation of the Spray Videos:

Application Directly Beneath the Nozzle:

[0086] The application of the melt-applied adhesive is to take place directly beneath the nozzle. Any deviation to the left or right is undesirable. A template mask is used for evaluation.

Assessment:

[0087] 0=The application of the melt-applied adhesive takes place directly beneath the nozzle in a straight line with a maximum deflection of 0.5 cm. [0088] 1=The filaments of the melt-applied adhesive do not even reach the substrate since they are too significantly deflected or the melt-applied adhesive filaments are deflected to such an extent that they do not reach the substrate in a straight line or do so with a deflection of more than 0.5 cm.
Deflection of Fine Filaments from the Template Mask or Formation of Angel Hair:

[0089] What is being described in this case is the deflection of the spray filaments in or counter to the direction of coating, considering only the spray width of 2.5 cm. If the application of 2.5 cm is exceeded or fine filaments fly over the substrate and do not reach it, this is referred to as angel hair.

Assessment:

[0090] 0=no deflected filaments [0091] 0.5=filaments up to 0.5 cm deflected [0092] 1=filaments up to 1 cm deflected [0093] 2=filaments up to 2 cm deflected [0094] 3=filaments up to 3 cm deflected [0095] 4=filaments larger than 3 cm deflected

[0096] FIG. 3 depicts spraying onto a roll. From this viewing angle, it is very readily possible to determine the deflection of the spray filaments in and counter to coating direction.

Rating:

[0097] The rating represents the total number of points. The smaller the number, the better the sprayability.

Sprayability:

[0098] The fewer total points that are obtained in the evaluation, the better the sprayability of the melt-applied adhesive examined. 0 points means a sprayability of 100%, 11 points a sprayability of 0%.

[0099] Tables 2a to 2c show, by way of example, the evaluation of the 14 spray tests at 140° C. using the melt-applied adhesive composition according to Example 3a. Table 3 shows the sprayability in % for all melt-applied adhesive compositions tested.

TABLE-US-00006 TABLE 2a Parameters and results of the assessment for experiments 1 to 5 Parameter 1 2 3 4 5 Temperature in ° C. 140 140 140 140 140 Speed of the pump in % 13 13 26 26 35 Amount of melt-applied adhesive in g/min 3.90 3.90 7.46 7.46 10.64 Distance of nozzle from the substrate in cm 4 4 4 4 4 Air pressure on the nozzle in bar 2 3 2 3 1 Evaluation of the spray pattern Visual impression of the spray pattern 1 1 0 0 0 Edge stability 0 0 0 0 0 Deflection of the filaments (from the template mask) 0 0 0 0 0 Fine filaments 0 0 0 0 0 Evaluation of the video Application directly beneath the nozzle 0 0 0 0 1 Deflection of fine filaments from the template 0 0 0.5 0.5 0.5 mask or formation of angel hair Rating 0 1 0.5 0.5 1.5 Sprayability in % 90.91 90.91 95.45 95.45 86.36

TABLE-US-00007 TABLE 2b Parameters and results of the assessment for experiments 6 to 10 Parameter 6 7 8 9 10 Temperature in ° C. 140 140 140 140 140 Speed of the pump in % 35 35 35 35 35 Amount of melt-applied adhesive in g/min 10.64 10.64 10.64 10.64 10.64 Distance of nozzle from the substrate in cm 4 4 4 4 4 Air pressure on the nozzle in bar 2 2.5 3 3.5 4 Evaluation of the spray pattern Visual impression of the spray pattern 0 0 0 1 0 Edge stability 0 0 0 0 0 Deflection of the filaments (from the template mask) 0 0 0 0 0 Fine filaments 0 0 0 0 0 Evaluation of the video Application directly beneath the nozzle 1 1 1 1 0 Deflection of fine filaments from the template 0.5 0.5 0.5 1 1 mask or formation of angel hair Rating 1.5 1.5 1.5 2.5 1.5 Sprayability in % 86.36 86.36 86.36 77.27 86.36

TABLE-US-00008 TABLE 2c Parameters and results of the assessment for experiments 11 to 14 Parameter 11 12 13 14 Spr. Temperature in ° C. 140 140 140 140 Speed of the pump in % 73 73 91 91 Amount of melt-applied 22.91 22.91 28.27 28.27 adhesive in g/min Distance of nozzle from 4 4 4 4 the substrate in cm Air pressure on the 2 3 2 3 nozzle in bar Evaluation of the spray pattern Visual impression of the 0 0 0 0 spray pattern Edge stability 0 0 0 0 Deflection of the 0 0 0 0 filaments (from the template mask) Fine filaments 0 0 0 0 Evaluation of the video Application directly 1 1 1 1 beneath the nozzle Deflection of fine 1 0.5 1 1 filaments from the template mask or formation of angel hair Rating 2 1.5 2 2 1.68 Sprayability in % 81.82 86.36 81.82 81.82 84.74 Spr.: sprayability

[0100] Table 3 shows the sprayability in % for all melt-applied adhesive compositions tested.

TABLE-US-00009 Formulation Temperature Sprayability 3a 140° C. 84.7% 3a 160° C. 82.8% 3b 140° C. 87.3% 3b 160° C. 77.9% 3c 140° C. 81.5% 3c 160° C. 88.6%

[0101] As can be inferred from Table 3, it was possible to assess the sprayability of an adhesive and/or the polymer using the detailed breakdown of the individual assessment criteria. Based on this method, it was possible to demonstrate that the sprayability of the degraded polymer has distinctly improved and a much larger application window, for example in relation to air pressure variation, temperature and application amount in g/min or g/m.sup.2, could be achieved.