Use of fluorinated compounds to confer release properties

Details Use of fluorinated compounds to confer release properties Use of fluorinated compounds to confer release properties

2001-02-28

2003-02-04

Cameron, Erma (Department: 1762)

Coating processes

With post-treatment of coating or coating material

Heating or drying

C427S421100, C427S439000

Reexamination Certificate

active

06514567

ABSTRACT:

The present invention relates to compounds to confer release properties to cellulose supports.
Specifically, the invention relates to the treatment of cellulose supports, such as paper, cardboard, etc., with particular fluorinated derivatives such as to confer release properties. With “release” the capability of the treated surface to allow an easy manual release of adhesives, such as for example labels, is meant.
It is known in the prior art that labels are commercialized on paper supports treated with high amounts of silicone polymers to confer release properties which imply an easy manual release of the labels from the paper supports. In EP 608,780 a fluorosilicone composition is described which applied to the surface of various substrata, such as for example, paper, synthetic textiles, after a suitable thermal crosslinking treatment at high temperature, causes the formation of a film which confers to the paper release properties towards adhesive substances. The drawback of the use of the above mentioned fluorosilicone compositions resides in that they require an application process wherein the treating composition is applied to the substratum dissolved in an organic solvent. The commonly used organic solvents are aromatic, aliphatic and halogenated hydrocarbons, which are generally flammable and/or toxic liquids. These treatments cannot therefore be carried out on line, (directly in paper mill), but they require specific plants. A further drawback consists in that after the solvent evaporation, a crosslinking phase of the silicone polymer at high temperature, in the range 100-150° C., is necessary.
When aqueous silicone dispersions are used, the conferred release properties are worsened with respect to the case when the silicone dispersions are dissolved in an organic solvent.
The need was felt to have available products capable to confer improved release properties, applicable from completely aqueous formulations or aqueous formulations containing reduced amounts of co-solvent, with the maximum value of 10% with respect to water, without requiring a crosslinking phase at high temperature.
The Applicant has unexpectedly and surprisingly found specific compounds able to overcome the above mentioned drawbacks of the prior art, improving the release properties conferred to cellulose supports when said compounds are applied from aqueous or prevailingly aqueous formulations.
An object of the present invention are therefore fluorinated compounds and their use to confer release properties to cellulose substrata, said fluorinated compounds being selected from the following structures:
(A) [R
f
—CFY—L—O]
m
P(O) (O
−
Z
+
)
3−m
(B) (O
−
Z
+
)
2
P (O) [O—L—YFC—O—R
f
—CFY—L—O—P(O)(O
−
Z
+
)]
m′
——[O—L—YFC—O—R
f
—CFY—L—O]P(O) (O
−
Z
+
)
2
(C) Fluorinated (meth)acrylic copolymers
(D) [R
t
—CF
2
—SO
2
N (U
1
) (U
2
)—O]g—P(O) (OZ)
3−g
in the compounds of structure (A) and (B) the following definitions mean:
m′ is an integer from 0 to 20, preferably from 0 to 4;
L is an organic group selected from —CH
2
—(OCH
2
CH
2
)
n
—, —CO—NR′—(CH
2
)
q
—, with R′═H or C
1
-C
4
alkyl group;
n=0-8, preferably 1-3, q=1-8, preferably 1-3;
Z═H, alkane metal or a NR
4
group with R═H or C
1
-C
4
alkyl group;
Y═F, CF
3
;
m=1,2,3, preferably 1,2;
Rf has a number average molecular weight in the range 350-8,000, preferably 500-3,000 and it comprises repeating units having at least one of the following structures, statistically placed along the chain:
(CFXO), (CF
2
CF
2
O), (CF
2
CF
2
CF
2
O), (CF
2
CF
2
CF
2
CF
2
O), (CR
4
R
5
CF
2
CF
2
O) , (CF CF
3
) CF
2
O), (CF
2
CF(CF
3
)O),
wherein
X=F, CF
3
;
R
4
and R
5
, equal to or different from each other, are selected from H, Cl, or perfluoroalkyl from 1 to 4 carbon atoms;
in the structure (D) the following definitions mean:
Rt is a linear or branched when possible perfluorocarbon radical having from 1 to 20 carbon atoms, preferably from 6 to 10 carbon atoms;
U
1
, U
2
equal to or different from each other, are selected from linear or branched C
1
-C
8
alkyl groups, (CH
2
CH
2
0)
Q
ethylenoxide groups, wherein
Q
is in the range 1-20, preferably 1-4;
g is an integer in the range 1-3.
Mixtures of two or more of the compounds (A), (B), (C) and (D) can also be used.
In particular Rf in the structures (A) and (B) can have one of the following structures:
1) —(CF
2
O)
a′
—(CF
2
CF
2
O)
b′
—
 with a′/b′ in the range 0.5-2, extremes included, a′ and b′ being integers such as to give the above mentioned molecular weight;
2) —(C
3
F
6
O)
r
—(C
2
F
4
O)
b
—(CFXO)
t
—
 with r/b=0.5-2.0; (r+b)/t is in the range 10-30, b, r and t being integers such as to give the above mentioned molecular weight, X has the above mentioned meaning;
3) —(C
3
F
6
O)
r′
—(CFXO)
t′
—
 t′ can be 0;
 when t′ is different from 0 then r′/t′=10-30, r′ and t′ being integers such as to give the above mentioned molecular weight; X has the above indicated meaning;
4) —(OCF
2
CF(CF
3
))
z
—OCF
2
(R′f)
y
—CF
2
O—(CF(CF
3
)CF
2
O)
z
—
 wherein z is an integer such that the molecular weight is the above mentioned one;
 y is an integer between 0 and 1 and R′f is a fluoroalkylene group having for example 1-4 carbon atoms;
5) —(OCF
2
CF
2
CR
4
R
5
)
q
—OCF
2
(R′f)
y
—CF
2
O— (CR
4
R
5
CF
2
CF
2
O)
s
—
 wherein:
 q and s are integers such that the molecular weight is the above mentioned one;
 R
4
, R
5
, R′f, y have the above mentioned meaning;
6) —(C
3
F
6
O)
r′″
(CFXO)
t′″
—OCF
2
(R′f)
y
—CF
2
O(CF(CF
3
)CF
2
O)
r′″
(CFXO)
t′″
—
 wherein
 r′″/t′″=10-30,
 r′″ and t′″ being integers such as to give the above mentioned molecular weight;
 R′f and y having the above mentioned meaning.
In the above indicated formulas:
—(C
3
F
6
O)— can represent units of formula —(CF(CF
3
)CF
2
O)— and/or —(CF
2
—CF (CF
3
)O)—
In the structure (A) wherein Rf is monofunctional, the other end group is of the T—O— type, wherein T is a (per)-fluoroalkyl group selected from: —CF
3
, —C
2
F
5
, —C
3
F
7
, —CF
2
Cl, —C
2
F
4
Cl, —C
3
F
6
Cl; optionally one or two F atoms, preferably one, can be replaced by H.
Among the compounds of structure (A) the following compounds are already known for other applications:
m=2, Rf of structure 3) wherein t′=0, r′=1-8, Z=H, alkaline metals, optionally substituted ammonium ion, T=—C
2
F
5
, —C
3
F
7
;
m=1 and Rf having structure 1)-6), T=perfluorinated group optionally containing one chlorine atom.
The mentioned fluoropolyethers (A) and (B) are obtainable by the well known processes in the prior art, see for example the following patents herein incorporated by reference: U.S. Pat. Nos. 3,665,041, 2,242,218, 3,715,378, and EP 239123. The functionalized fluoropolyethers having hydroxyl termination are for example obtained according to EP 148482, U.S. Pat. No. 3,810,874.
The preparation of the monofunctional (per)fluoropolyether phosphates of structure (A) can be carried out by reacting the corresponding hydroxy-terminated (per) fluoroalkylenoxides with POCl
3
. To obtain the monoester derivative (m=1) it is necessary to use a molar ratio POCl
3
/hydroxy-terminated compound in the range 2/1-10/1, preferably 6/1-8/1. The reaction is carried out by slowly dropping the hydroxy-terminated compound in POCl
3
, at a temperature between 50 and 100° C., preferably between 70° and 80° C., removing the HCl vapours in a KOH trap. The POCl
3
excess is removed by distillation while the formed adduct is hydrolysed by H
2
O. The separation of the obtained product takes place by extraction with a suitable organic solvent, such as for example ethyl acetate. The product of structure

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