EP1189957A1

EP1189957A1 - Aqueous vinyl and/or acrylic polyamide and polymer dispersions

Info

Publication number: EP1189957A1
Application number: EP00927363A
Authority: EP
Inventors: Karine Loyen; Philippe Guinot; Reinhard Linemann
Original assignee: Atofina SA
Current assignee: Arkema France SA
Priority date: 1999-05-21
Filing date: 2000-05-16
Publication date: 2002-03-27
Also published as: AU4577200A; WO2000071594A1; FR2793800A1

Abstract

The invention concerns aqueous dispersions containing a water dispersible polyamide and an acrylic, vinyl and/or styrene polymer. Said dispersions can be obtained either by mixing two dispersions, one containing the polyamide and the other the acrylic, vinyl and/or styrene polymer, or by preparing the latter in the presence of the polyamide. Whatever the mode of preparation from 50 to 99 % of the polyamide chains are bound by a covalent bond to the acrylic, vinyl and/or styrene polymer.

Description

AQUEOUS DISPERSIONS OF POLYAMIDES AND VINYL AND / OR ACRYLIC POLYMERS

The invention relates to the field of aqueous dispersions and in particular to aqueous dispersions based on polyamides and more particularly to dispersions based on polyamides and acrylic vinyl and / or styrenic polymers.

In general, aqueous dispersions find their interests in numerous applications. In particular those relating to the surface treatment of different materials such as wood, metal, paper, leather and glass. By way of non-limiting indication, mention may be made of paints, adhesives, varnishes, glues, etc.

Dispersions based on acrylic, vinyl and / or styrenic polymers give complete satisfaction. However, for particular applications, it is sometimes advantageous to have dispersions consisting either of a mixture of particles of acrylic, vinyl and / or styrenic polymers and of particles of polycondensates such as polyamides, polyesters or polyesteramides, or particles of acrylic, vinyl and / or styrenic polymers stabilized by polycondensates such as polyamides, polyesters or polyesteramides, playing the role of protective colloids.

These two types of dispersions give rise to microstructured composite materials, the advantages of which are: resistance to hydrolysis, filmification at low temperature without the addition of co-solvent or plasticizer and without surface tack (paint application); obtaining materials that perfectly meet the flexibility / mechanical strength compromise required by applications such as, for example, cosmetics (nail polish, hair lacquers).

However, the use of polycondensates as protective colloids gives additional properties to the dispersions: in particular better control of the particle size and of the homogeneity of the composite material, making it possible to improve the optical qualities. (gloss and transparency) of the films, a significant reduction in the quantity of surfactants used in synthesis thus eliminating the problems linked to the migration of these into the films (sensitivity to water, loss of adhesion). To achieve this type of dispersion EP 292261 proposes the emulsion polymerization of unsaturated monomers in the presence of a predispersed polyester, WO 90/1 0665 describes a dispersion based on polyester grafted by the polymerization of vinyl monomers in the presence of an unsaturated organopolysiloxane . Likewise WO 97/281 98, WO 95/01 382 and EP 532961 describe a process based on the overpolymerization of a polyester.

Generally, the polymerization of one or more monomers in the presence of already formed particles is designated by "overpolymerization". US 5,277,978 describes in particular the use of a functionalized sulfate and sulfonate polyester as a protective colloid to stabilize a dispersion. It is recommended to use less than 0.5 to 10% of protective colloids compared to the monomers to obtain clear and transparent films. WO 98/03567 describes a process by overpolymerization from a water-dispersible polyamide. This does not contain unsaturated groups in the chains or at their ends. The overpolymerization of vinyl or styrenic acrylic monomers in the presence of these polyamide dispersions leads to an intimate mixture of two polymers containing at least 10% by weight of polyamides.

It has been found that in a certain number of applications such as coatings, adhesives, the use of a dispersion consisting of an intimate mixture of at least two polymers can cause a problem of phase separation between the two. polymers, this resulting in poor application properties and above all very poor mechanical strength of the coating obtained. The Applicant has found that a solution to this problem is to create interactions between the polyamide and the acrylic, vinyl and / or styrene polymer. These interactions can be of different natures and concern all or only part of the polyamide chains. Furthermore, it has been found that in a certain number of applications such as coatings (paint, paper, textile, leather) it was desirable to use polymer dispersions of fine size, less than 150 nm preferably to have good application properties (filming, gloss) without using an excess of micromolecular surfactants which migrate into the films and deteriorate their properties: sensitivity to water, loss of adhesion to the support.

The Applicant has found that the use of polyamide as a protective colloid enables it to manufacture dispersions of acrylic, vinyl and / or styrenic polymers of small size, preferably less than 120 nm, stable to hydrolysis, with very little micromolecular surfactants.

One of the objects of the invention is an aqueous dispersion of polymer particles with a diameter between 20 and 500 nm and preferably less than 1 20 nm consisting of: - 0.1 to 1 00% by weight of the total weight of the particles of water-dispersible polyamides and

- 0 to 99.9% by weight of the total weight of the particles of acrylic, vinyl and / or styrenic polymers.

The dispersion of the invention can be obtained without a micromolecular surfactant, however the addition of this at a content lower than what is commonly used in this field can improve the stability of the dispersion.

The polymer particles can represent up to 40% by weight of the dispersion. From 50 to 99% of polyamide chains are grafted by covalent bond to acrylic, vinyl and / or styrenic polymers. The cohesion between the polymers forming the dispersion is ensured by this type of bond. This prevents any phase separation at the time of implementation, thus allowing the application properties of the dispersion to be preserved and surface coatings having good mechanical strength to be obtained.

The polyamides used to make the dispersion of the invention are water-dispersible (PAHD) and contain at the ends of 0.5 to 2 polymerizable double bonds per chain. They are designated below by PAHDI. The hydrodispersibility of these polyamides is obtained thanks to the presence of a certain fraction of sulfonate groups (strong neutralized acid). The average level of sulfonate group per PAHD chain is from 0.5 to 49% by mole and preferably from 3 to 25% by mole.

PAHDs are easily dispersed in water in the form of individualized particles relatively polydispersed in size with an average diameter of between 20 and 600 nm.

Due to the presence of strong neutralized acid groups (sulphate) on the copolyamide chains located at the periphery of the particles, the dispersions obtained in this invention exhibit great chemical stability (addition of salts, increase in ionic strength, addition of bases or acids), which distinguishes them from the conventionally obtained dispersions which contain weak acid groups on the surface and whose chemical stability is relatively weak. This property is useful in the paint formulation stages. However, the stability of these dispersions can be further increased in a conventional manner by using unsaturated monomers carrying weak acid groups.

The dispersions of the invention can be obtained by the emulsion polymerization of at least one vinyl, acrylic and / or styrene monomer (A) in the presence of at least one water-dispersible polyamide having at the ends of 0.1 to 2 unsaturations by chain (PAHDI). To prepare the dispersions of the invention, the procedure is as follows:

Firstly, PAHDI is prepared by polycondensation and functionalization using a chain limiter according to the procedure described later, then an aqueous dispersion is preferably prepared, from 0.1 to 40% by weight of the polyamide and introduced into the bottom of the reactor vessel. The temperature of the medium is brought to the usual temperatures for emulsion polymerizations (conventionally from 50 ° C to 80 ° C). The monomer (s) (A) or the mixture (s) of acrylic, vinyl and / or styrenic monomers is then poured at constant speed onto the dispersion according to the semi-continuous processes or sequences known from the skilled in the art. An initiator solution of the type of those conventionally used as an emulsion is poured in parallel into the reactor so as to initiate the radical polymerization of the monomer (s). Optionally, a first pouring of hydrophilic monomers can be carried out before adding, in a second step, the mixture (s) of more hydrophobic monomers to promote a reverse core-shell mechanism and obtaining small particles. . A weakly concentrated solution of micromolecular surfactant can also be poured. The monomer A is chosen from the group containing:

1. Relatively hydrophilic monomers such as C-1 -C3 alkyl or hydroxyalkyl amides and esters of (meth) acrylic acids and other unsaturated acids, acrylic, methacrylic and itaconic acids, vinyl alcohol esters, acrylonitrile, methacrylonitrile, crotonaldehyde, (meth) acrylates carrying hydrophilic groups such as segments based on polyoxyethylene.

2. Hydrophobic monomers such as:

The C3-C1 2 '' alkyl (meth) acrylates ^are styrenic, vinyl, diene, (meth) acrylates containing a substituted nitrogen atom such as t-butyl aminoethyl methacrylate, diethyl methacrylate aminoethyl. The preferred monomer A is chosen from: acrylic acid methacrylic acid

(meth) acrylate substituted by hydroxyalkyls (HEMA, etc.)

(meth) acrylates substituted by Cn, n <3 alkyl styrene butyl acrylate ethyl hexyl acrylate

(meth) octyl acrylate.

The polyamides used are obtained by polycondensation and functionalization using a chain limiter carrying an unsaturated group which can be polymerized by the radical route.

In general, polycondensation is carried out between a diacid and a diamine. The water dispersibility is obtained thanks to a monomer, in general a diacid containing the unit resulting from a salt of an alkali metal of 2 or 1-sulfoisophthalic acid, the salt being able to be a salt of sodium, potassium or lithium, or amine corresponding to the following formula:

X - Na, K, Li As diacids, mention may be made of: isophthalic, adipic, azelaic, sebacic, dodecandioic, butane-dioic, 1,4-cyclohexyl dicarboxylic, terephthalic acids (fatty acids less than 12% by weight), fatty acids dimerized (these dimerized fatty acids preferably have a dimer content of at least 98%; preferably they are hydrogenated; they are marketed under the brand "PRIPOL" by the company "UNICHEMA", the the most interesting grades are the PRIPOL 1 008, the PRIPOL 1 009 and the PRIPOL 101 3 or under the Empol brand by the company HENKEL).

As diamines, mention may be made of hexamethylenediamine, tetramethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 1, 5-diamino-hexane, 2,2,4-trimethyl-1, 6-diamino-hexane, piperazine , 3,3'-dimethyl-4,4'diaminodicyclohexylmethane, 4,4'-diamino-dicyclohexyl-methane, 2,2 '- (4,4'- diaminodicyclohexyD-propane, isophoronediamine, 1, 4-diamino-cyclohexane, meth-xylylene-diamine It is also possible to use polyol diamines sold under the name "Jeffamine" by the company Huntsman Corp. The preferred grades are Jeffamine D400 and Jeffamine D2000. polyethers in particular increase the hydrophilicity of the resins, their weight content can reach up to 60%.

Diacids and diamines can be replaced by amino acids or lactams such as caprolactam, enanthalactam, laurolactam, their open forms and 1 1 -amino-undecanoic acid.

As chain limiter one can use:

Unsaturated compounds, carriers of the above-mentioned groups, which can belong to different classes of organic compounds. They can be in particular of the type R ¹ R ² C = CR ³ X (1) where the groups or atoms R ¹ , R ² , R ³ , similar or different, are: H, halogen, alkyl, aryl, in particular phenyl , and carboxyl, norbornyl, thienyl, pyrrolyl or furanyl, while the active group X can be:

- (CH ₂ ) _n COOH with n = 0 to 1 7; -CH ₂ NH (CH ₂ ) ι ι COOH; - (OCH ₂ CH ₂ ) kOH with k = 20

-COO-glycidyl;

YC ₆ H ₄ - (CH ₂ ) _n , - COOR with n '= 0 or 1, Y being -COO, -CONH, R being H, alkyl or aryl;

-CH ₂ OH; - (CH ₂ ) _m IMH ₂ with m = 0 to 1 8 or - (OCH ₂ CH ₂ ) OH. Thus, particularly favorable examples of the compounds according to formula (1) are: acids or esters of unsaturated acids, acrylic, methacrylic, cinnamic, crotonic, citraconic, itaconic, vinylacetic, undecylenic, maleic, fumaric, 5'-norbornene-2 acrylic, 3'-furanyl-2 acrylic, 3'-pyrrolyl-2 acrylic, N-allyl aminobezoic, N-acryloyl or N-methacryloyl p-aminophenylacetic, N-allyl amino-1 1 -undecanoic, and the like.

Another type of unsaturated compound, suitable for the process according to the invention, may be possible without being limited: acids and N-maleimido esters: hexanoic, p.benzoic, dodecanoic, etc. Mention may also be made of anhydrides and imides derived from anhydrides such as tetrahydrophthalic, p. Benzoic N-maleimido, p- (endo-cis-bicyclo (2,2, 1) -5 heptene-2,3 dicarboxylic).

When preparing the dispersions of the invention, it is necessary that the number of PAHDI particles in the reactor is large enough so that the monomer can be added and polymerized at high speeds. Depending on the composition and characteristics of the copolyamide used, there is an optimal window in which these conditions are obtained (for a minimum concentration value of 0.1%). We have also observed that the interactions between the monomers and the polyamide vary according to the polarity of the monomers used. It is therefore necessary to optimize the synthesis process (temperature, nature of the initiators) according to the nature of the polyamide and of the vinyl or acrylic monomers overpolymerized.

Compared to conventional dispersions obtained by polymerization and which generally contain from 1 to 3 parts of low-mass surfactants which can diffuse out of paint films, the dispersions obtained by this invention from 0.1 to 10% by weight of polyamide, have the advantage of having small sizes, preferably less than 1 00 nm and of containing only very small quantities of micromolecular surfactants and a majority proportion of surfactant of high mass which has the effect of limiting as much as possible species likely to migrate into movies. In addition, the grafting of the polyamide to the copolymer acrylic, vinyl and / or styrene described in the present invention completely suppresses the migration of this macromolecular surfactant out of the film. This property limits the deterioration of the films over time, in particular eliminating the phenomena of exudation, sensitivity to water and loss of adhesion to the substrates.

These polyamides, initially water-dispersible, when they are used at more than 10% by weight on the total quantity of polymer, are capable of providing, by their particular structure, superior mechanical reinforcement of the films obtained when these latexes are formulated for different applications (paint, textile, paper, leather). The grafting increases the interactions between the acrylic, vinyl and / or styrene polymer and the polyamide and thus promotes synergies of physico-mechanical properties.

The behavior of the dispersion with respect to the usually used mineral fillers can be improved by the presence at the periphery of the latex particles of a polyamide carrying an ionic and / or polar group. The grafting claimed in the invention can stabilize the interactions between mineral fillers and latex particles during the formation of the paint film, thus ensuring better cohesion and better resistance to abrasion, in particular to wet abrasion. Furthermore, similarly to the dispersions of acrylic, vinyl and / or styrenic copolymers obtained on unsaturated polyesters, the use of a water-dispersible polyamide carrying polymerizable unsaturated groups claimed in the invention promotes the adhesion of the films obtained on the substrates polyamide type. Similarly, this same grafting promotes adhesion between the substrate and the film in applications such as nail varnishes and the treatment of nonwovens.

Taking into account the literature, the absence of ester-type bonds in the polyamide used increases, compared to the water-dispersible polyesters which are unsaturated or not described in the literature, the stability of this dispersing agent during the overpolymerization stage and in certain applications. requiring heat treatment. The following examples illustrate the invention without limiting its scope.

Comparative example:

Preparation of a water-dispersible PA without unsaturation (PAHD).

We operate in a reactor of 4 liters capacity, with three pipes: gas inlet, communication with a distillation system comprising a condenser connected to a distillate receiver, as well as an anchor stirrer. In this reactor, we introduce:

339.0g of lactam 6 or 3.0 mole, 1 96.5g of AH salt (adipic acid and hexamethylenediamine salt) or 0.75 mole, 205.3g of hexamethylenediamine or 1 .767 mole, 1 68.5g of isophthalic acid either

1 .01 5 mole, 1 61 .0 mono sodium salt of isophthalic sulfo acid or

0.6 mole and 50g of water.

The reactor is purged with nitrogen, then heated with all valves closed to 200 ° C material in 1 hour, the pressure is then 6.0 bar. Then, with stirring, the temperature rose in 1 hour to 240 ° C, the pressure is then 15 bars. The reaction is allowed to take place at 240 ° C. material for 4 hours, the pressure reaches at the end of the 4 hour plateau 18 bar and stabilizes, which means firstly that all the monomers react and secondly that the equilibrium of amide formation is achieved. At this point, the relaxation begins, which lasts 90 minutes, the material temperature at the end of the relaxation is 270 ° C. A stream of nitrogen of 30 l / h is passed through for 15 minutes and the PAHD is taken out of the reactor, collected in a cooled tray to ensure rapid solification.

The product obtained is white, brittle, odorless. The average molecular weight in shade measured, by viscosimetry (inherent viscosity of 0.33) is 6500g / mole, the glass transition temperature (Tg) is 89 ° C (measured by DSC: 10K / min). PAHD is easily dispersible in water up to 40% by weight. The particle size of the dispersion is 1,00 nanometers. Examples according to the invention Example 1: Preparation of a water-dispersible unsaturated polyamide (PAHDI) monounsaturated with cinnamic acid. The procedure is identical to that of the comparative example except that the reagents introduced into the reactor are: 339.0g of lactam 6, ie 3.0 mole, 196.5g of AH salt (salt of adipic acid and hexamethylenediamine), or 0.75 mole, 1 87.34 g of hexamethylenediamine or 1.61 5 mole, 1 68.5 g of isophthalic acid or 1 .01 5 mole, 1 61 .0 of mono sodium salt of isophthalic acid is 0.6 mole, and 22.5 g of cinnamic acid or 0.1 52 mol which corresponds to one unit of cinnamic acid per PAHDI chain and 50 g of water.

The product obtained is slightly yellow, brittle, odorless. The number-average molecular mass measured by viscosimetry is 6650 g / mole. The Tg is 89 ° C (measured by DSC: 10K / min). PAHDI is easily dispersible in water up to 40% by weight. The particle size of the dispersion is 62 nanometers.

Example 2: Preparation by introducing all the monomers from a mono unsaturated PAHDI functionalized with crotonic acid.

The procedure corresponds to that of Example 1, except that instead of cinnamic acid is charged 1 3.1 g of crotonic acid or 0.1 52 mole, which corresponds to one unit of crotonic acid per PAHDI chain.

The product obtained is slightly yellow, brittle, odorless. The number-average molecular mass measured by viscosimetry is

6600g / mole. The Tg is 83 ° C (measured by DSC: 10K / min). PAHDI is easily dispersible in water up to 40% by weight. The particle size of the dispersion is 1 00 nanometers.

Example 3: Preparation by introducing all the monomers from a PAHDI partially functionalized with 0.5 equivalents of crotonic acid per PAHD chain.

The operating mode corresponds to that of Example 1, except that: 339.0g of lactam 6 or 3.0 mole, 1 96.5g of AH salt (adipic acid and hexamethylenediamine salt) or 0.75 mole, 205.3g of hexamethylenediamine or 1 .767 mole, 1 68.5g of isophthalic acid or 1 .01 5 mole, 1 61 .0 of mono sodium salt of isophthalic sulfo acid is 0.6 mole, and 6.5 of crotonic acid is 0.076 mole which corresponds to 0.5 unit of cinnamic acid per PAHDI chain and 50g of water.

The product obtained is slightly yellow, brittle, odorless. The Mn (target) is 6600g / mole. The Tg is 90 ° C (measured by DSC: 10K / min). PAHD is easily dispersible in water up to 40% by weight. The particle size of the dispersion is 1,00 nanometers.

Example 4:

In a 2 I jacketed reactor equipped with a condenser and purged with nitrogen, 300 g of a polyamide dispersion, described in the comparative example, containing 5.0% of dry extract are added. The reactor is purged with nitrogen and the temperature is brought to 75 ° C. at 150 rpm. When the temperature is reached and stabilized, 200g of the mixture of monomers consisting of 92.0g of methyl methacrylate, 104.0g of butyl acrylate and 4.0g of acrylic acid and a solution of 0.8g of initiator TBHP (Terbutylhydroperoxide) in 25 ml of water and a solution of 0.28 g of FORMOPON activator (sodium salt of formaldehyde sulfoxylate) in 25 ml of water are drained off in 300 min. After 90 min of polymerization, a solution of 1.23 g SDS in 25 ml of water is poured in 21 0 min.

After the end of the addition, the reaction medium is maintained at 75 ° C. for 60 min, then cooled to room temperature and filtered through a 100 micrometer filter. The dry extract and the particle size were then determined (Table 1).

Example 5: Preparation of dispersions according to the invention.

Example 5.1 using the PAHDI of Example 1. In a 20 I double-jacket reactor equipped with a condenser and purged with nitrogen, 300 g of a polyamide dispersion, described in Example 1 of the invention, containing 5.0% of dry extract, are added.

The reactor is purged with nitrogen and the temperature is brought to 75 ° C. at 150 rpm. When the temperature is reached and stabilized, 200g of the mixture of monomers consisting of 92.0g of methyl methacrylate, 104.0g of butyl acrylate and 4.0g of acrylic acid and a solution of 0.8g of initiator TBHP (Terbutylhydroperoxide) in 25 ml of water and a solution of 0.28 g of FORMOPON activator (sodium salt of formaldehyde sulfoxylate) in 25 ml of water are drained off in 300 min. After 90 min of polymerization, a solution of 1.23 g SDS in 25 ml of water is poured in 21 0 min.

Example 5.2: Using the PAHDI of Example 2 in the Procedure of Example 5.1

The dry extract and the particle size were then determined (Table 1).

Example 5.3: using the PAHDI of Example 3 in the procedure of Example 5.1.

The dry extract and the particle size were then determined (Table 1). The dry extract and the particle size of the dispersions obtained from the polymerization seeds described in the example outside the invention and the three examples were determined and are indicated in Table 1: Table 1: results

Claims

1. Aqueous dispersion of polymer particles with a diameter between 20 and 500 nm and preferably less than 1 20 nm consisting of:

- 0.1 to 1 00% by weight of the total weight of the particles of water-dispersible polyamide

2. Dispersion according to claim 1 characterized in that the water-dispersible polyamide contains on average from 0.1 to 2 polymerizable unsaturations per chain.

3. Dispersion according to claim 1 or 2 characterized in that from 50 to 99% of polyamide chains are grafted by covalent bonds to acrylic, vinyl and / or styrenic polymers.

4. Dispersion according to any one of the preceding claims, characterized in that the water-dispersible polyamide represents at least 10% by weight of the total weight of the polymer particles.

5. microstructured film as can be obtained by application and drying of the dispersion of claim 4.