Solid coating composition for textile floor coverings

A solid coating composition based on a polyolefin containing a filler is disclosed. The polyolefin is partly or completely reacted with either an unsaturated organic acid or an unsaturated organic acid anhydride.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to coating compositions for textile floor 
coverings. 
2. Discussion of the Background 
Heavy coating compositions for carpets based on amorphous 
poly(alpha-olefins) (APAO) have been known for years in addition to those 
made of bitumen, PVC, and polyurethane mixtures. A typical formulation 
made up of approximately 30% of a thermoplastic binder and 70% of a 
filler. Examples of binders are atactic polypropylene (APP) of various 
grades (product of homoor copolymerization) or specific atactic co- and 
terpolymers. From the last mentioned group, propylene/1-butene/ethylene 
terpolymers, propylene/ethylene, 1-butene/ethylene, and 1-butene/propylene 
copolymers have proved particularly useful. 
Isotactic polypropylene (IPP), resin, wax, or paraffin can optionally be 
added for selective modification of properties. Powdered limestone is used 
primarily as filler, and also barite in some cases. 
The solid coating composition is ordinarily applied as a hot-melt adhesive 
to carpet upper materials treated in various ways, that carry a latex or 
hot-melt precoat. In this regard, for example, refer to B. H. Koerner, 
"The Use of Atactic Polypropylene Using The Example of Solid Carpet 
Coating", Kunststoffe 65, pages 467 f., 1975. Carpet tiles are the 
preferred field of use for the coating compositions. 
With increasing use of carpet tiles in residences, hospitals, banks, etc., 
the specifications for a good solid coating composition are constantly 
increased. The deficient stability under load of the carpet tiles made 
with atactic polyolefins is frequently criticized. Under high load, such 
as under legs of chairs or tables, or when walked on with high heels, 
permanent impressions are made or damage occurs that impair the lay or the 
dimensional stability of the tiles. The reasons for this is the plastic 
deformation of the coating composition under the influence of a load. This 
phenomenon is called "cold flow". 
Cold flow can be reduced by adding IPP or by using higher molecular weight 
atactic polyolefins. However, the flexibility, and thus the lay, are 
unfavorably affected by this. Problems can also occur in processing 
because of the increased melt viscosity of the composition. In addition, 
solid coating compositions with high proportions of IPP tend to shrink 
because of the recrystallization process. To achieve a balanced property 
profile, it is therefore generally attempted in practice to limit the 
addition of IPP to the amount that is just necessary. 
There is therefore a strongly felt need for a solid coating composition 
that can be processed by the conventional hot-melt technique and also has 
the property of partial elastic recovery in addition to a low depth of 
penetration under load, i.e., low cold flow. 
SUMMARY OF THE INVENTION 
Accordingly, it is an object of this invention to provide a solid coating 
composition. 
It is another object of this invention to provide a solid coating 
composition which can be processed by the conventional hot-melt technique. 
It is another object of this invention to provide a solid coating 
composition which has the property of partial elastic recovery. 
It is another object of this invention to provide a solid coating 
composition which has a low depth of penetration under load, i.e., low 
cold flow. 
The inventors have now surprisingly discovered a novel solid coating 
composition which satisfies all of the above objects of this invention, 
and other objects which will become apparent from the description of the 
invention given hereinbelow. 
The invention provides a solid coating composition comprising a 
polyolefin-based thermoplastic binder containing a filler. The polyolefin 
is partly or completely reacted with an unsaturated organic acid or an 
unsaturated organic acid anhydride.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a first embodiment (A) of the present invention the IPP fraction of the 
binder ordinarily used to improve the stability under load is completely 
or partly replaced by a predominantly crystalline polyolefin that has been 
functionalized in a suitable way by reaction with organic acids containing 
double bonds or a corresponding acid anhydride. 
In another embodiment (B) of the present invention the proportion of 
atactic polyolefin in the conventional solid coating compositions is 
partly or completely replaced by an amorphous polyolefin (of low 
crystallinity) that is functionalized in the same way. 
In embodiment (A) above, 0 to 15 wt.% of nonfunctionalized IPP is present 
in the binder in addition to the functionalized, predominantly crystalline 
polyolefin. In embodiment (B) above, the nonfunctionalized, atactic 
polyolefin is present in the binder in a range of from 0 to 95 wt.%. 
Examples of polymers that can be used in accordance with embodiment (A) 
include: 
Polypropylenes grafted with acrylic acid, methacrylic acid, or fumaric 
acid. Belonging to this class of compounds, for example, are the POLYBOND 
grades sold by BP Chemicals Limited. 
Polypropylenes grafted with maleic anhydride. Examples of appropriate 
polymers are sold by the Himont Co. under the name HERCOPRIME. 
Maleic acid, monoalkyl maleates, monoalkyl fumarates, and aconitic acid are 
also suitable unsaturated acids. 
In addition to polypropylene, propylene/ethylene copolymers, 
propylene/1-butene copolymers, 1-butene/ethylene copolymers, or a mixture 
of polypropylene and the copolymers mentioned can also be used. 
In general, the graft polymers of polypropylene are prepared by 
conventional graft polymerization of the unsaturated acids or anhydrides 
in the presence of the graft substrate and a radical-former. Peroxides, 
azo compounds, or high-energy radiation can be used as the latter. Typical 
synthetic examples are listed in European Patent Application Disclosure 0 
188 926, Belgian Patent 692 301, Japanese Patent 27 421/66, or U.S. Pat. 
No. 3,499,819. 
The polymers functionalized in this way are added to the binder in an 
amount of approximately 1 to 20% by wt., preferably 3 to 12% by wt. (based 
on the binder). To produce an adequate effect, the acid number of the 
functionalized polymer should be greater than 10 mg KOH/g, preferably 40 
to 60 mg KOH/g (determined for anhydrides after prior ring-opening with 
water). Processing viscosities acceptable in practice are obtained when 
the MFI 230/2 of the graft polymer is greater than 30 g/10 min., 
preferably 40 g/10 min. 
Polymers pursuant to embodiment (B) are prepared by radical grafting of 
amorphous polyolefins with maleic anhydride or fumaric acid, for example. 
Particularly suitable amorphous polyolefins are the 
propylene/butene/ethylene terpolymers of Huels AG available under the 
trade name VESTOPLAST, corresponding to German Patent 29 30 108, for 
example. Such graft polymers are synthesized in solution or in the melt in 
the presence of peroxides. Appropriate examples are described, for 
example, in German Patent Application Disclosure 15 46 982, East German 
Patent 20 232, German Patent Exposition 26 32 869, and in the Journal of 
Applied Polymer Science, Vol. 13, pages 1625 ff. (1969). 
The functionalized atactic polyolefin of embodiment (B) is present in the 
binder in a range of from 2 to 97 percent by weight. 
It should be noted that degradation of the base polymer is frequently 
observed during the radical grafting. This degradation can manifest itself 
negatively particularly in the presence of tertiary carbon atoms in the 
polymer chain, since cold flow and thus the depth of penetration after 
loading is found from experience to increase with decreasing molecular 
weight. However, the positive effect that can be produced by introducing 
carboxyl groups far outweighs the negative effect of peroxidic degradation 
of the polymer. 
Amorphous polyolefins that contain polybutadiene can also be used. German 
Patent Publication 27 08 757 discloses the promoting effect of 
polybutadiene on the degree of grafting during the grafting reaction. When 
using this grafting aid, partial crosslinking of the polymer takes place 
at the same time. If starting polymers containing double bonds are used 
(for example, propylene/ethylene/1,5-hexadiene terpolymers), it is not 
necessary to add peroxides since the grafting then takes place purely 
thermally by way of an ene-reaction (cf. for example, German Patent 
Application 24 01 149 or U.S. Pat. No. 3,260,708). When grafting in the 
melt, carrying out the process in an extruder pursuant to U.S. Pat. No. 
3,862,265 has advantages. Alternatively, however, a batch process can also 
be used in a mixing vessel. 
A suitable amorphous graft polymer has an acid number of 2 to 40, 
preferably 3 to 10 mg KOH/g (determined for anhydrides after prior 
reaction of the anhydride group with water and removal of the fractions 
not covalently bonded). In the case of grafting with maleic anhydride this 
corresponds to an maleic anhydride content of 0.26 to 0.9 wt.%. 
Any monomer (such as maleic anhydride) not bonded covalently during the 
grafting reaction in fact has no negative effect on the mechanical 
properties of the coating composition. However, to avoid odor 
contamination, it can easily be reacted with longchained alcohols or 
amines to form the corresponding half-ester or amide. 
The melt viscosity of the amorphous graft polymer at 190.degree. C. is in 
the range between 300 to 60,000, preferably 1,000 and 20,0000 mPa s. The 
melt viscosity desired in the binder can be selected by varying the 
proportion of wax, resin, or IPP. In general, solid coating compositions 
that are readily processable are obtained with a filler fraction of 70 
wt.% when the binder has a melt viscosity at 190.degree. C. of 5,000 to a 
maximum of 20,000 mPa s. 
A binder additive of 3 to 5% isotactic polypropylene with an MFI 190/5 of 
70 g/10 min. in addition to the amorphous graft polymer has proved to be 
beneficial particularly when emphasis is placed on maximum load stability 
of the compositions without impairing the flexibility or processing 
viscosity to an unallowable extent. 
Suitable fillers are powdered limestone, barite, and mica. Preferred in all 
cases is a powdered limestone with particle size distribution between 24 
and 192 .mu.m (a useful commercial product, for example, is the Jura-White 
filler, grade G.Gr.Al. of Kalksteinwerk Ulm). The filler content can vary 
between 50 and 85 wt.% and is preferably 70%. The highest contents of 
filler are possible when using atactic polyolefins of high molecular 
weight and with high 1-butene content. 
In the case of maleic anhydride-grafted polymers, addition of water to open 
the ring of the anhydride is not necessary; apparently, the traces of 
moisture present on the filler surface suffice for this. 
The composition containing filler are generally prepared in mixing vessels 
purged with inert gas by first melting the atactic component (for example, 
APAO or maleic anhydride-grafted APAO) and then mixing it with the 
isotactic polymer (for example IPP or functionalized IPP) at a temperature 
of 200.degree. C. until a homogeneous mixture is formed. After adding 
viscosity regulators such as wax and resin, the filler is then worked in. 
To test the mechanical properties, pressed plates (10.times.10.times.0.2 
cm) are prepared from the solid coating composition (melt in a die at 
190.degree. C.; pressure time 10 min. at 150.degree. C.; storage time 
after production: 48 h at room temperature). The depth of penetration of a 
round 1 cm.sup.2 ram is measured on this plate after 4 hours of loading at 
50 kp/cm.sup.2 ("4-hour stability test"), and the recovery power 
(remaining depth of penetration) is measured 10 min. after removing the 
load. The first measured parameter is a measure of the stability under 
load, and the second provides an indication of the elastic properties of 
the composition. 
Comparison of conventional formulations with the newly developed 
formulations shows that replacing IPP by functionalized isotactic polymers 
or replacing APP or APAO by an amorphous graft polymer in solid coating 
compositions produces stabilities under load that are at least 40% better, 
i.e., reduced depths of penetration under load. Based on improved recovery 
power, the remaining deformation or depth of penetration is distinctly 
less. 
In practice, for example, this means that comparatively smaller amounts of 
functionalized isotactic polymer can be used to produce the same 
stabilities under load as those normally achieved only with higher 
proportions of IPP. In this way, the processing viscosity of the 
composition can be limited to an acceptable level. Other benefits of the 
newly developed solid coating compositions are found in reduced shrinkage 
and improved lay of the carpet tiles coated in this way because of greater 
flexibility. 
Other features of the invention will become apparent in the course of the 
following description of exemplary embodiments which are given for 
illustration of the invention and are not intended to be limiting thereof. 
APAO 1: An amorphous propylene/1-butene/ethylene terpolymer with a melt 
viscosity at 190.degree. C. of 8,000 mPa s and a penetration 100/25/5 (by 
the method of DIN 52 010) of 20 0.1 mm. 
APAO 2: An amorphous propylene/1-butene/ethylene terpolymer with a melt 
viscosity at 190.degree. C. of 50,000 mPa s and a penetration 100/25/5 (by 
the method of DIN 52 010) of 15 0.1 mm. 
APAO 3: An amorphous 1-butene/propylene/ethylene terpolymer with a melt 
viscosity at 190.degree. C. of 8,000 mPa s and a penetration 100/25/5 (by 
the method of DIN 52 010) of 15 0.1 mm. 
IPP 1: Isotactic polypropylene with MFI 190/5 (by the method of DIN 53 753, 
Code T) of 70 g/10 min. 
Wax 1: Polyethylene wax with a drip point of 120.degree. C. and an average 
molecular weight of 1,600. 
Resin 1: Aliphatic hydrocarbon resin with a softening point (ball and ring) 
of 100.degree. C. and an average molecular weight of 2,400. 
KP-P 1: Polypropylene grafted with 6% acrylic acid with MFI 190/5 of 64 
g/10 min. 
KP-P 2: Polypropylene grafted with 2% maleic anhydride with an intrinsic 
viscosity of 0,7 100 m1/g. 
In all cases, 0.2 parts of IRGANOX B 225 (CibaGeigy) is added as 
stabilizer. 
The powdered limestone used as filler is Jura White G.Gr. Al. 
COMISON EXAMPLES 
Preparation and properties of conventional solid coating compositions 
95 parts of APAO 1 is mixed with 0.2 parts of stabilizer in an oil-heated 
tank blanketed with nitrogen and is melted at 200.degree. C. 5 parts of 
IPP 1 is worked in with a stirrer. The finished binder is treated with 
powdered limestone in a 30:70 ratio and the mixture is homogenized. The 
properties of the binder obtained are summarized in Table 1, Composition 
A. 
Compositions B and C of Table 1 are likewise conventional solid coating 
compositions. They are also used for comparison with the compositions 
pursuant to the invention described below. 
EXAMPLE 1 
Preparation and properties of a solid coating composition that has been 
modified with a polypropylene grafted with acrylic acid. 
95 parts of APAO 2 is mixed with 0.2 parts of stabilizer in an oil-heated 
mixing vessel blanketed with nitrogen and is melted at 200.degree. C. 5. 
parts of KP-P 1 is mixed in with a stirrer and the finished binder is 
treated with powdered limestone in a 30:70 ratio. The mixture is 
homogenized. The properties of the solid coating composition are 
summarized in Table 2, Composition D. 
EXAMPLE 2 
The procedure is the same as in Example 1, but this time the KP-P 1 is 
replaced by the same amount of KP-P 2. The properties of this solid 
coating composition are described in Table 2, Composition E. 
EXAMPLE 3 
IPP in the conventional solid coating composition C (See Table 1) is 
replaced by the same weight of KP-P 1. The properties of the Composition F 
thus prepared are summarized in Table 2. 
EXAMPLE 4 
To prepare an amorphous maleic anhydride-graft polymer (of low 
crystallinity), 450 g of APAO 1, 11.25 g of maleic anhydride, blanketed 
with nitrogen, and heated to 180.degree. C. at a heating rate of 2.degree. 
C/min. With continuous kneading, the composition is left for 30 minutes 
longer at this temperature and is then processed further directly to the 
solid coating composition. The graft polymer after reaction with water and 
purification by precipitating it twice from toluene solution with 
isopropanol) has a melt viscosity at 190.degree. C. of 5,000 mPa s, a 
softening point (DIN 52 011) of 104.degree. C., and a penetration (DIN 52 
010) of 15 0.1 mm. 
95 parts of graft polymer, 5 parts of IPP 1, and 0.2 parts of stabilizer 
are blanketed with nitrogen in a mixing vessel and are melted with 
stirring at 200.degree. C. To the finished binder is added powdered 
limestone in a 30:70 ratio and the mixture is homogenized. the properties 
of the solid coating composition are summarized in Table 3, Composition G. 
EXAMPLE 5 
450 g APAO 2 is grafted with maleic anhydride under the same conditions as 
in Example 4. The amorphous grafted polymer obtained has an acid number of 
4.2 mg KOH/g, a melt viscosity at 190.degree. C. of 19,000 mPa s, a 
softening point of 107.degree. C., and a penetration of 14 0.1 mm. All of 
the parameters were determined in the same way as in Example 4. 
Following the procedure of Example 4, the solid coating composition H is 
obtained, whose properties are shown in Table 3. 
EXAMPLE 6 
In the same way as described under Example 4, 450 g of APAO 2 is grafted 
with 22.5 g of maleic anhydride in the presence of 2.7 g of dicumyl 
peroxide. The amorphous grafted polymer obtained has an acid number of 8.8 
mg KOH/g, a melt viscosity at 190.degree. C., and a penetration of 10 0.1 
mm. All parameters were determined in the same way as in Example 4. 
Following the method of Example 4, the solid coating composition I is 
obtained (Table 3). 
TABLE 1 
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Properties And Composition of Conventional Solid Coating Compositions 
Composition Compn. A Compn. B Compn. C 
__________________________________________________________________________ 
APAO 28.5 pts. 
APAO 1 
28.5 pts. 
APAO 2 
11.4 pts. 
APAO 2 
APAO -- -- 11.4 pts. 
APAO 3 
IPP 1.5 pts. 
IPP 1 1.5 pts. 
IPP 1 1.2 pts. 
IPP 1 
Wax -- -- 3 pts. 
Wax 1 
Resin -- -- 3 pts. 
Resin 1 
Filler 70 pts. 
powdered 
70 pts. 
powdered 
70 pts. 
powdered 
limestone limestone limestone 
Properties of the binder 
Melt viscosity at 190.degree. C. 
12 500 
mPa s 68 000 
mPa s 14 000 
mPa s 
Penetration (DIN 52 010) 
17 0.1 
mm 10 0.1 
mm 11 0.1 
mm 
Softening point (DIN 52 011) 
159.degree. C. 
160.degree. C. 
158.degree. C. 
Properties of the solid coating composition 
Depth of penetration of a 1 cm.sup.2 ram after 
1.4 mm 0.5 mm 0.71 mm 
4 h loading with 50 kp/cm.sup.2 in a 
2 mm pressed plate 
Remaining depth of penetration 10 min. after 
1.22 mm 0.33 mm 0.60 mm 
removing load, 
recovery to 
__________________________________________________________________________ 
TABLE 2 
__________________________________________________________________________ 
Properties And Composition of Solid Coating Compositions That Were 
Modified 
With Crystalline Polyolefins Functionalized by Carboxyl or Acid Anhydride 
Groups 
Composition Compn. D Compn. E Compn. F 
__________________________________________________________________________ 
APAO 28.5 pts. 
APAO 2 
28.5 pts. 
APAO 2 
11.4 pts. 
APAO 2 
APAO -- -- 11.4 pts. 
APAO 3 
Cryst. graft polymer 1.5 pts. 
KIP-P 1 
1.5 pts. 
KP-P 2 
1.2 pts. 
KP-P 1 
Wax -- -- 3 pts. 
Wax 1 
Resin -- -- 3 pts. 
Resin 1 
Filler 70 pts. 
powdered 
70 pts. 
powdered 
70 pts. 
powdered 
limestone limestone limestone 
Properties of the binder 
Melt viscosity at 190.degree. C. 
67 000 
mPa s 50 000 
mPa s 14 000 
mPa s 
Penetration (DIN 52 010) 
10 0.1 
mm 10 0.1 
mm 11 0.1 
mm 
Softening point (DIN 52 011) 
159.degree. C. 
147.degree. C. 
158.degree. C. 
Properties of the solid coating composition 
Depth of penetration of a 1 cm.sup.2 ram after 
0.28 mm 0.25 mm 0.22 mm 
4 h loading with 50 kp/cm.sup.2 in a 
2 mm pressed plate 
Remaining depth of penetration 10 min. after 
0.13 mm 0.10 mm 0.11 mm 
removing load, 
recovery to 
__________________________________________________________________________ 
TABLE 3 
__________________________________________________________________________ 
Properties And Composition of Solid Coating Compositions That Were 
Modified With Amorphous Maleic Anhydride Graft Polymers 
Composition Compound G Compound H Compound I 
__________________________________________________________________________ 
Amorphous Maleic Anhydride 
28.5 pts. 
gr. poly. 
28.5 pts. 
gr. poly. 
28.5 pts. 
gr. poly. 
graft polymer from Example 4 
from Example 5 
from Example 6 
IPP 1.5 pts. 
IPP 1 1.5 pts. 
IPP 1 1.5 pts. 
IPP 1 
Filler 70 pts. 
powdered 
70 pts. 
powdered 
70 pts. 
powdered 
limestone limestone limestone 
Properties of the binder 
Melt viscosity at 190.degree. C. 
11 000 
mPa s 24 000 
mPa s 23 000 
mPa s 
Penetration (DIN 52 010) 
17 0.1 
mm 11 0.1 
mm 12 0.1 
mm 
Softening point (DIN 52 011) 
159.degree. C. 
159.degree. C. 
158.degree. C. 
Properties of the solid coating composition 
Depth of penetration of a 1 cm.sup.2 ram after 
0.55 mm 0.34 mm 0.29 
mm 
4 h loading with 50 kp/cm.sup.2 in a 
2 mm pressed plate 
Remaining depth of penetration 10 min. after 
0.41 mm 0.15 mm 0.14 mm 
removing load, 
recovery to 
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Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein.