Binder for leather finishing composition comprises latex of acrylic copolymer including units derived from monomer containing ureido or thioureido group

The present invention relates to products binders for leather finishing, finishing on the products incorporating these binders and on the leathers thus treated.

In the finishing of leather, it is well known to those skilled in the art that the finishing is dependent on the quality of the skin. For full grain leathers or flowers corrected, finishing, without changing the appearance of the grain, should have some protection to the support. However, on a crust, finishing systematically pigmented serves to replenish an artificial flower and provides the required characteristics depending on the end use of the leather.

Opposite to the variety of appearance of the leather and the diversity of making, it is unable to process all of the supports with the same substances and finishing in a single application. Therefore, the surface state and the characteristics of each category of leather therefrom, as well as the use will be made are determinants in choice of products finishing for use.

However, the gait employed is nearly always the same: a dressing is substantially made by the successive application of primer layers of different nature. The finishing or final thickness of the coating will depend on the quality of the support. It is between 10 and 15 mm for a full grain leather, 40 and 60 for a leather [...] corrected, and can reach 200 [...] for a varnish or crust leather coated.

Typically, a dressing is made, according to the quality of the leather and the end use, by two or three superposed layers. The first, contacting the leather and generally highly flexible, constitutes the bottom layer. According to the final application, it may be transparent but colored or pigmented thus cover. The second layer fails or is generally an average hardness. Covers It is generally colored but little. The outer layer, called fixative or "top coat" is always transparent. It is this part which is most stressed and which should have a high hardness (between 60 and 90 Shore A), good rub resistance sec or in the presence of water and good adhesion.

For [...] The resins are often in solution in organic solvents or sometimes in aqueous emulsion. Binders for [...] The commonly used are polyurethanes, protein binders, binders or nitrocellulose that are often formulated with a crosslinker. There are few [...] aqueous emulsion that are most often polyurethanes, as those sold under the denominations [...] ® 60, 80, 85 or 90 UD by the company BAYER, and sometimes acrylic copolymers, as those sold under the denominations [...] AQS® or PC by the company [...] & [...].

[...] to improve the grip performance products currently known for finishing leather, the Company was found that the use as a binder in at least one of the individual layers constituting a leather finishing on of an acrylic copolymer in aqueous dispersion obtained by emulsion copolymerization of a different comonomers, or a portion thereof has a ureido-type function, can increase adhesion of the finishing on the leather, without degrading the other application properties. The latter are particularly hardness, friction resistance and the dynamic resistance to water penetration.

The present invention therefore first binder for a composition to be applied as layer leather finishing, said finish layer can be a primer layer, a layer of a layer fails or fixative, characterized by the fact that it consists of an acrylic latex obtained by emulsion copolymerization of ethylenically unsaturated comonomers radically polymerizable, one of the monomers or a portion of these monomers having a functional group (I):

X

II

c

/\

NH (I)-N

I I

wherein X is 0 or S.

The functional group (I) above can be part of the group of formula (II):

X

II

C

/\

NH (II)-N

L_{2 R}

wherein:

-X is as defined above; and

-R^{1 and} R^{2 each represent a hydrogen atom or} alkyl group of C ^-Cg, in particular in C^-C ^,^{or together form a chain-} (CH_2)n- with n = 2 to 4, which may be substituted up to two times by alkyl group of C C ^ - ^ and/or hydroxy and/or alkoxy or_Cl-C 4 which may be interrupted by a carbonyl;

or the group of formula (III):

X

C

R^j- n nh (iii) 3/^x

\/

A

wherein:

-X is as defined above;

-R represents a hydrogen atom or an alkyl group in 3^{C i-Cg}, in particular ^-Cg C; and

-A is a trivalent hydrocarbon group C_{2 ~} C_{4 which may be substituted} up to two times by alkyl C C_{1 ~4 and}/or hydroxy and/or alkoxy ~_C 1 C_{4 or} which may be interrupted by a carbonyl.

The comonomers The or groupings of formula (I) may in particular be chosen from the compounds of formula (IV) or (V):

X

C C

/ \ /\

R-n nh (iv) r^j- n nh (v)

R^{1'l \} 2/A

R

in which:

X, R, R and R are as defined above; and R^{4 is} a residue which contains at least one ethylenic unsaturated bond C=C, radically polymerizable.

The remainder R^{4 can be selected among}:

ch =_{cr 5-} 2

ch_{2-ch = cr} 5- 2

ch = 0 cr^5- c-

II

O

OH

ch = 0 cr^d- ch_0-O-ch_0- ch-(ch₀₎ " 2,2-2^{K 2} ' n_{5 I}

OH

_AOE280A2AO> CH_{2 =} CR^5- CH_2- 0-CH-CH_2- 0 - (CH_2)n-

OH

_AOE280A2AO> =_{cr 5 ch 2-ch2-O}-ch_2- ch-ch-_nh- 2 (ch₂₎-

_AOE280A2AO> CH_{2 =} CR^5- 0 - (CH_2)n-

_AOE280A2AO> =_{cr 5 ch 2-O}-ch_2- c-o-(ch₂₎-

O

_AOE280A2AO> CH_{2 = CR} C-^5- 0 - (CH_2)n-

0

_AOE280A2AO> CH_{2 =} CR^5- C-NH-(CH_2)n-

O

_AOE280A2AO>_{2 ch =} cr^5- nh-(ch₂₎-

_AOE280A2AO> ch_{0 =} cr^5- c-O-ch- 0 c-nh-(ch₀₎ "-

2, jj

O 0

_AOE280A2AO> =_{cr 5 ch 2-O}-ch_2- c-nh (CH₂₎-_n-

0

_AOE280A2AO> N-Di-(3-Allyloxy-2-Hydroxypropyl) Aminoalkyl,

with R = Η, CH_{3 and} η = 1 to 8, but is not limited to.

Exemplary or comonomers of the formula (III), include:

-n-vinyl ethylene urea;

-n - (2- [...] ) ethylene urea;

-n-di-(3-allyloxy-2-hydroxypropyl) aminoethyl ethylene urea;

-n - (2- [...] ) ethylene urea;

-n - (2-acryloyloxyethyl) ethylene urea;

n- [...] -urea;

the ethylene-allyl alkyl ureas;

-n - (2- [...] ) ethylene urea;

-n - (2- [...] ) ethylene urea ;

-N- (2-methacryloyloxyethyl) ethylene urea [or 1 - (2-methacryloyloxyethyl imidazolin-2-one];

-n - (2-acryloyloxyethyl) ethylene urea;

-n - (2- [...] ) ethylene urea;

-n - (2- [...] ) ethylene urea;

-n - (3-allyloxy-2-hydroxypropyl) aminoethyl ethylene urea;

n-the-( [...] ) ethylene urea;

n-the-(acrylamidomethyl) ethylene urea;

-n- [...] ethylene urea;

-n- [...] ethylene urea;

-n- [...] ethylene urea;

n- [...] -; and

-n - [3 - (1,3- [...] -2-one) [...] ] methacrylamide.

Synthetic comonomers to ureido function Particularly preferred are N-(2-methacryloyloxyethyl)-ethylene urea [or (l-(2-methacryloyloxyethyl)-imidazolin-2-one] and the N( 2- [...] ) ethylene urea.

Preferably, the one or more comonomers functional group (I) represent from 0.1 to 20% by weight, in particular 1 to 5% by weight, of the total comonomer composition; the extract sec acrylic latex according to the invention is typically between 30 and 70% by weight; and the size of the particles of said latex is in particular between 50 and 250 nm.

The comonomers other than those to functional groups (I) are preferably selected so that the copolymer has the glass transition temperature Tg suitable, by the combination, well known to those skilled in the art, of monomers capable of conducting homopolymers having a high Tg with monomers capable of conducting to homopolymers with a low Tg. Tg suitable The depends on the finish layer to which the binding agent is intended: and, is used generally a copolymer having a low Tg (or between 10° and -50 C) in the case of a binder designed to enter into the composition of a back layer of; Tg intermediate a (either between -30 and +30°C) in the case of a binder designed to form part of a layer of fails; and a high Tg (either between -10 and 50 °C) in the case of a binder designed to enter into the composition of a layer fixative, these ranges being that as indicative data.

Exemplary monomers capable of conducting to homopolymers with a low Tg, include ethyl acrylate, butyl acrylate, 2-ethyl hexyl acrylate, 1' nonyl acrylate, vinyl 2-ethyl hexanoate, andc.

Exemplary monomers capable of conducting homopolymers having a high Tg, include methyl methacrylate, vinyl acetate, styrene, acrylic acid, methacrylic acid, 1' acrylamide, andc.

The latex according to the invention, leading to homogeneous particles, is prepared by emulsion copolymerization under the conditions well known to those skilled in the art:

-The reaction is preferably carried out under inert atmosphere in the presence of radical initiators. The priming system used may be a Red-Ox as^{K 2}_0g S 2, ( [...] ^)_{2 Og} S 2/^{Na 2S 2} ° 5 '^{Na 2S0 3}'^{a thermal system} as (NH_{4)2 0g} S 2, the amounts used being included between 0.2 and 1.0% by weight relative to the total mass of the monomers, preferably between 0.25 and 0.5% by weight;

the polymerization reaction according to 1 'invention is carried out at a temperature of between 50 and 85" C and is a function of the nature of the initiator system used: 50-75' C for the systems-based Red-Ox peroxodisulfate and metabisulphite, 70-85°C thermal ink-peroxodisulfate single base;

the preparation of dispersions according to the invention is carried out preferably according to a method of semi-continuous type, for limiting drifts composition that are the basis of differences in reactivity of the different monomers. The introduction of the monomers into a pre-emulsion with a portion of the water and a surface-active agent is thereby generally performed for a period of time of 3 to 5 hours 30 hours. It is also useful, although not indispensable, perform seeding of 1 to 15% of the monomers. The systems emulsifiers used in the emulsion polymerization process are selected from the range of emulsifiers having a suitable hydrophilic/lipophilic balance. Preferred systems are formed by the combination of an anionic surfactant, such as sodium laurylsulfate, the nonylphenol ethoxylated sulphate in particular 20-25 moles of ethylene oxide, benzene dodecylsulphonate and ethoxylated fatty alcohol sulfates, and a nonionic surfactant, such as ethoxylated nonylphenols in particular 10-40 moles of ethylene oxide and ethoxylated fatty alcohols ;

the total amount of emulsifier is generally in the range of 1 to 5% by weight and preferably from 2 to 4% by weight based on the monomers.

The present invention also relates to a composition to be applied as layer leather finishing, characterized in that it is a binder formed by:

(a) 2-100 parts by weight of at least one latex as defined above; and

(b) 0-98 parts by weight of at least one other selected from acrylic latex, polyurethane and polyurethane-acrylic.

Furthermore, the composition of the present invention can further comprise a crosslinker that allows crosslinking at low temperature acrylic emulsions, in particular a cross-linking agent selected from the polycarbodiimides, hydrazides, polyaziridine compounds, dialdehydes and polyepoxides, and/or, in the case where the (s) latex has acid (s), a crosslinker capable of reacting with said acid functions, and chosen in particular from the polycarbodiimides, hydrazides, polyaziridine compounds and polyisocyanates, the amount-of crosslinker (s) up to 20% by weight, in particular 1 to 10% by weight, relative to the (x) latex (dispersion particle (s)) (a) and (b) above.

In the case especially where said composition is for forming a primer layer or a layer of fails, it may further include at least one pigment in an amount of up to 70 parts by weight per 100 parts by weight of component (a) more, optionally, the component (b). The amount of pigment depends, inter alia, the type of the pigment.

The composition according to the present invention may further include at least one additive selected from:

-waxes, such as polyethylene waxes (PE) and polyamide (Pa);

-coalescing agents, such as glycol ethers and glycol ether esters;

-solvents for promoting spreading or penetration, such as ethanol and 1' isopropanol (IPA);

-spreading agents, such as diglycol;

-anti-foaming agents, such as fatty acid or ethoxylated fatty acids.

Furthermore, the extract sec of the composition according to the present invention is generally 10,20%, the value of said extract sec could be adjusted by adding water to said composition.

The present invention also provides leathers treated with a composition as defined above.

The following Examples illustrate the present invention without, however, limit the scope. In these Examples, the parts and percentages are by weight unless otherwise specified.

In the Example 1, the amounts of the ingredients of the formulations and monomers are expressed in parts of active materials.

Examples In the application 3 and 4, the leather used was a full grain calf skin semi-finished, [...] to 1.6-1.8 mm, the Company " [...]", and the characteristics of the different finishes have been determined by means of the following tests, known to those skilled in the art.

Bonding of the finishes on the leather was evaluated using a 90° peel test. A test piece has been bonded with a cyanoacrylate glue, finishing side, on an aluminum support having an area of 10 x 50 mm^2. Using a traction machine (speed 50 mm/min.), by measuring the force at break of six test tubes.

The dynamic resistance to water penetration of finishes has been measured using a penetrometer BALLY, according to the standard NFG 52015 adapted to determine the kinetics of water absorption as a function of time. To this end, were measured, after wiping light, the weight gain of four test tubes after 1, 3, 5 and 7 hours of bias on the penetrometer BALLY. According to the habit of those skilled in the art, the water uptake of a well water repellent finishing must be less than 30% after 3 hours of contact.

The rub resistance sec or in the presence of solvents: acetone, ethanol and water, has been determined in accordance with the standard NFG 52301, by using a friction [...] (the score ranges from 1 to 5:5 is judged very good and 1 is judged very bad).

The burst strength has been determined on ten test pieces according to the standard NFG 52007.

it

The flexural strength has been determined using a flexometer BALLY on six identical test pieces according to the standard IUP 20.

The gloss 60° has been determined using a three-beam-degree meter, in accordance with ISO 2813-73. Through the fact that the roughness of the leather can vary greatly from sample to sample, the different [...] have also been applied to cards normalized contrast. The given value for each coating were the average of 12 measurements per sample-

In a reactor for 3,1, equipped with a hot water circulation in the double casing, central agitation and a condenser, is introduced a stock formulated as follows:

_AOE280A2AO> Water 75.0 parts

_AOE280A2AO> on nonylphenol ethoxylated with 25 moles

ethylene oxide to 35% in

water (marketed by the

[...] Society in the

denomination [...] NOS 25) 0.30 portion

Sodium metabisulphite 0.30 portion

The homogenizes and 55 °C sub nitrogen (it is maintained during the entire duration of the synthesis).

When the temperature of the stock reaches 55 °C, is cast, in 15 minutes, 10% of the pre-emulsion and solution of the initiator, which are formulated as follows:

_AOE280A2AO> Water 69.00 parts

_AOE280A2AO> on nonylphenol ethoxylated with 25 moles

ethylene oxide to 35% in

water ( [...] NOS 25) 2.70 parts

_AOE280A2AO> Monomers 100.0 parts

Initiator solution

_AOE280A2AO> Water 6.00 parts [...][...] 0.30 ammonium portion

Bearing is temperature for 15 minutes to 55 °C, is cast and the remainder of the pre-emulsion of the solution of initiator in the 2:00 30 min. A 80" C and is allowed to react for 2 additional hours.

Is cooled to room temperature, and the mixture is filtered on a web of 100 microns.

The latex were synthesized A to D from the monomers A to D such as listed in table 1, in which are also indicated the characteristics of the latex obtained.

Table 1

Are applied on a leather finishing in a layer, having the following composition:

_AOE280A2AO> Water 50 parts

_AOE280A2AO> Latex as denoted in the

first line of Table 2 30 parts

_AOE280A2AO> Pigment black sold under

the denomination "BLACK [...]"

by the company BAYER 2,0 parts

The dry substance content of the bottom layer is of 15%. The coating is applied using an air gun in a cross layer, the amount is deposited between 120 and 130 g/m. ° It is dried at 7,0 C for 20 minutes, and satin to 70" C for 15 seconds under a load of 1 ton/m.

Was measured peeling force, water absorption, friction resistance, burst strength, and the brightness of the finishes so obtained on the leather. The results are reported in Table 2.

(a) Tl corresponding to a control latex emulsion copolymers of acrylic esters that sold under the trade name " [...] 3911" by the Company ELF ATOCHEM

(b) T2 Latex control corresponding to a 50/50 mixture of emulsions of copolymers of acrylic esters sold under the denominations respectively " [...] 3911" and " [...] 3110" by the Company ELF ATOCHEM

(c) Latex E according to the present invention, corresponding to a 50/50 mixture of the latex B and emulsion " [...] 3911" above

(d) average over six measurements

There is thus a significant improvement in the adhesion of the primer layer obtained from the latex B other properties without degrading the application.

It is also found that the bottom layer obtained by mixing an emulsion of a copolymer comprising ureido groups (latex B) with a standard acrylic (E mixture) not only has good adhesion to the leather, but also a good dynamic resistance to penetration by water, and the mixture having the best properties of each latex taken separately. Furthermore, relative to the layer obtained from the latex T2, there is a improving the friction durability and wet adhesion, the resistance to the ingress of water, however, remaining equivalent.

Are applied on a leather finishing in two layers. The first layer or bottom layer had the following composition:

_AOE280A2AO> Water 50 parts

_AOE280A2AO> Latex T2 as defined in item (b)

of Table 2 30 parts

_AOE280A2AO> Pigment black (BLACK [...] of

cREAVIS BAYER) 20 parts

The basecoat formulation has a sec extract of 15%. It is applied using an air gun in a cross layer. The amount

, O

deposited is between 120 and 130 g/m. The basecoat is dried at 70" C for 20 minutes, and satin during 15 seconds to 70 °C under a load of the order of 1 ton/m^2.

The overcoat or fixative is applied in the same manner. Its composition is as follows:

_AOE280A2AO> Water 50 parts

_AOE280A2AO> Latex as denoted in the

first line of Table 3 30 parts

_AOE280A2AO> Pigment black (BLACK [...]

the Company BAYER) 20 parts

Furthermore, the dry solids content of the fixative is 15%. Unlike the normal use of a fixative that is generally transparent, has been introduced in the tests a pigment to allow a better assessment of the hold with regard to rubbing to sec or in the presence of solvents: water, acetone, ethanol, finishing. Said layer is dried at 70 °C during 20 minutes, and satin to 70 °C during 15 seconds under a load of 1 ton/m. The amount of

2 deposited fixative is between 100 and 120 g/m.

The [...] 1^{1 according to invention} are applied without difficulty on the bottom layer. Spreading of fixative was good. Different finishes The thus obtained have shown no stickiness (tack), and the hand of the leather was good.

The results are reported in Table 3 hereinafter.

(has) No fixative (bottom single layer)

(b) cross-linked latex: in the finishing composition, is added 10% by weight, based on the latex carbodiimide sold under the name "XL [...] SE 29" by the company UNION [...] ; applying the formulation, drying it and its glazing have been delivered to the conditions of the Example 3

(c) control latex T3 corresponding to a polyurethane emulsion that sold under the trade name® 80 [...] UD by the company BAYER

(d) control latex T4 corresponding to an acrylic emulsion that sold under the trade name® [...] AQS by the company [...] & [...].

In Table, means that the measurement has not been made

Binders comprising All l (- 2-methacryloyloxyethyl)-imidazolin-2-one have good adhesion to leather, that is greater than that of the different controls. C Compared to the reference composition, incorporating the l-(2-methacryloyloxyethyl)-imidazolin-2-one (composition B) also enhancing the flexural strength, without degrading the other application properties. The addition of a crosslinker, although leading to a decrease of adhesion which remains still greater than that of the composition C and better than a polyurethane emulsion, induces a decrease in water absorption and an increase in the resistance to the effect of friction in the presence of solvents (acetone and alcohol).