WO1999051431A1 - Water dispersible/redispersible hydrophobic polyester resins and their application in coatings - Google Patents

Abstract

This invention relates to the synthesis from PET (virgin, recycled, post consumer, or precursor raw materials) of novel water dispersible or water emulsifiable polyester resins having improved hydrophobicity or non-polar characteristics. These characteristics give the applied film of these dispersions or emulsions much improved water repellency while at the same time retaining their redispersible or re-emulsifiable properties. Such resins can be used for many applications in the paper, textile, coatings, paint, construction, and other industries.

Description

WATER DISPERSIBLE/REDISPERSIBLE HYDROPHOBIC POLYESTER RESINS AND THEIR APPLICATION IN COATINGS

FIELD OF THE INVENTION The present application is a continuation-in-part of pending U.S. Serial No.

08/792,635 filed January 31,1997. This invention relates to a process for coating the surface of a substrate with a water repellent coating composition comprising a polyester

resin. This invention also relates to the synthesis from polyethylene terephthalate (PET)

such as virgin PET, recycled PET, post consumer PET, or precursor raw materials of

novel water dispersible or water emulsiflable polyester resins having improved

hydrophobicity or non-polar characteristics. The present is invention also relates to

resins having excellent hydrophobic character, also good ability to orient the

hydrophobic groups away from substrates to which they are applied and high water drop

contact angles of the coated surface. The above characteristics give the applied film of these dispersions or emulsions much improved water repellency while at the same time

retaining their redispersible or re-emulsifiable properties. Such resins can be used for many applications in the paper, textile, coatings, paint, construction, and other

industries.

BACKGROUND OF THE INVENTION AND

DESCRIPTION OF THE PRIOR ART

Several patents have been written relating to the synthesis of water soluble,

dispersible, or emulsiflable polyester resins. For example, Altenberg, in U.S. Pat. No.

4,604,410, has proposed making etherified aromatic polyols by digesting scrap polyalkylene terephthalate with a low molecular weight polyhydroxy compound, containing 3-8 hydroxyl groups. A resulting intermediate is alkoxylated with 1-4 moles of ethylene oxide and/or propylene oxide. The final product is useful in making

polyurethane and polyisocyanurate foams.

Sperenza et al. U.S. Pat. No. 4,485,196 have recited reacting recycled

polyethylene terephthalate scrap with an alkylene oxide, such as propylene oxide. The

product can be used in making rigid foams.

Other methods of reacting scrap polyalkylene terephthalate with glycols or

polyols are proposed by Svoboda et al. in U.S. Pat. No. 4,048,104; and Altenberg et

al. U.S. Pat. No. 4,701,477. In applicant's previous invention (U.S. Pat. No.

4,977,191 to Salsman) there is disclosed a water-soluble or water-dispersible polyester

resin suitable for textile sizing applications. The polyester resin comprises a reaction

product of 20-50% by weight of waste terephthalate polymer, 10-40% by weight of at least one glycol and 5-25% by weight of at least one oxyalkylated polyol. Preferred

compositions also comprise 20-50% by weight of isophthalic acid. A further

water-soluble or water-dispersible resin comprises a reaction product of 20-50% by weight of waste terephthalate polymer, 10-50% by weight of at least one glycol and

20-50% by weight of isophthalic acid.

U.S. 5,252,615 to Rao et al teaches coating compositions derived from

alcoholysis of polyethylene terephthalate (PET). Most preferably, the PET is recycled

or reclaimed from plastic articles.

Dale et al. , in U.S. Pat. No. 4, 104,222, have proposed making a dispersion

of linear polyester resins by mixing linear polyester resin with a higher alcohol/ethylene

oxide addition-type surface-active agent, melting the mixture and dispersing the resulting melt in an aqueous alkali solution. The products are used as coating and impregnating

agents.

References proposing the use of copolymers containing terephthalic units and units derived from alkylene and polyoxyalkylene glycols for fiber or fabric treatment

include Hayes (U.S. Pat. No. 3,939,230), Nicol et al. (U.S. Pat. No. 3,962,152), Wada

et al. (U.S. Pat. No. 4,027,346), Nicol (U.S. Pat. No. 4,125,370) and Bauer (U.S. Pat.

No. 4,370,143).

Marshall et al. , in U.S. Pat. No. 3,814,627, have proposed applying an

ester, based on polyethylene glycol, to polyester yarn.

In our other patent U.S. 5,281,630 (Salsman), we disclose sulfonated water-soluble or water-dispersible polyester resin compositions made by treating a

polyester glycolysis product with an alpha, beta-ethylenically unsaturated dicarboxylic

acid and then with a sulfite.

The following U.S. Patents describe polyester resins containing fatty acid

moieties: 4,080,316; 4,179,420; 4,181,638; 4,413,116; 4,497,933; 4,517,334;

4,540,751; 4,555,564; 4,686,275; 5,075,417 and 5,530,059. None of the above patents

disclose the resins of the present invention which have excellent hydrophobic and high

contact angles when a drop of water is applied to surfaces coated with such resins.

The resins described in the above prior art have found applications in

textiles, coatings, and adhesive. All of these resins however have a fairly polar nature

which limits their use to adhesion promoters or coating applications where water

resistance is not a major factor or where the water resistance is being supplied by other additives. No mention of water repellent properties has been associated with these

polyester resins.

In some instances larger amounts of oils are fatty acids are used to supply

cross-linking and thermosetting properties to the polyester resins. This chemistry has

been labeled "alkyd" chemistry. During the drying phase cross-linking occurs between

chains, and the applied coating becomes insoluble.

To this date the inventor has no knowledge of prior polyester art where the

water dispersible or emulsifiable polyester resins of said art has incorporated enough

non-polar groups to supply hydrophobic character or properties to the substrate on which

these dispersions are applied and/or at the same time retain water redispersibility.

The main problem with most non-polar materials that have reactive condensation sites is that these materials have only one reactive site. (For example

stearic acid, oleic acid, palmitic acid, behenic acid, etc. These are most likely isolated from naturally occurring triglycerides such as vegetable and animal fats and oils.) This

means that in the polyester condensation reaction they become chain terminators and the amounts that can be used are severely limited because the greater the amount the less the

molecular weight of the resin. In alkyd chemistry advantage is taken from the

unsaturation in oils and cross linking reactions can be used. However reaction through

unsaturation does not expose sufficient areas of the oil modified chain to provide

hydrophobic and water repellent properties to the coatings produced from this chemistry .

The resins described in this invention have overcome the problem of chain

termination by using a highly modified polyester backbone. In this way polyester resins

can be made containing 30 percent or more of mono-functional monomers, such as stearic acid, to provide a much improved non-polar nature. Then, using reactions cited

in our previous patents, these resins can be made into water dispersions or emulsions. Because of the large amount of hydrophobic or non-polar functionality these resins

cannot be considered water soluble as some previous sulfonated resins have been. When

these dispersions or emulsions are applied to most substrates and dried, orientation of

the hydrophobic areas of the chain occurs and the surface of the substrate becomes water

repellent, with the degree of water repellency corresponding to the thickness and

concentration of the initial coating. This water repellency is obvious from the high

contact angle of a drop of distilled water placed on the substrate. This high contact angle is not evident in previous water dispersible resins.

The prior art is silent regarding the new water dispersible and polyester

resins of the present invention which are derived from polyethylene terephthalate and which exhibits high water repellency as evidenced by high contact angles.

OBJECTS OF THE INVENTION

It is a primary object of the invention to provide water-soluble or

water-dispersible polyester resin compositions having improved hydrophobicity.

It is a further object of the invention to provide water-soluble or

water-dispersible polyester resin compositions having improved hydrophobicity and

non-polar characteristics.

It is an additional object of the invention to provide water-soluble or

water-dispersible polyester resin compositions having improved water repellency. It is yet another object of the invention to provide water-soluble or

water-dispersible polyester resin compositions having improved oil and water-repellency .

An additional object of the invention is to utilize waste polyester material in

the production of polyester resins having improved hydrophobicity and non-polar

characteristics.

It is still another object of the invention to use the water-dispersible polyester compositions as coatings for fiber, paper or fabric.

It is yet a further object of the invention to produce water-soluble or

water-dispersible polyester coating compositions having improved oil and

water-repellency .

It is a still further object of the invention to provide a process for coating the surface of a substrate with the instant water dispersible polyester composition, thereby

imparting water and oil repellency to said substrate.

SUMMARY OF THE INVENTION

Briefly, the present invention relates to water dispersible/and redispersible

hydrophobic polyester resins derived typically from PET, especially recycled PET

having improved hydrophobicity or non-polar characteristics. The present invention is

directed to polyester resins having the following general formula:

In " P " A_m wherein I is the ionic group; n is an integer in the range of 1-3 and defines the number

of ionic groups; P is a polyester backbone; A is an aliphatic group; and m is an integer

in the range of 3-8 and defines the number of aliphatic groups.

The ionic groups I which are required for water-dispersibility are typically

derived from a carboxylic acid group which is introduced into the resin by polyacid

monomers. The weight percent of ionic monomers in the resin is from 1 % to 20%

percent, with 5 to 10% of ionic monomer being preferred.

The backbone P of the polymer is composed of polyester groups. It can be

any linear or branched polyester made using polyacids and polyalcohols. The preferred

method is to generate the backbone using polyester from recycled sources. The weight percent of the polyester backbone ingredients range from 30-80% of the whole resin,

with the most preferred being 50-60% by weight.

The aliphatic groups A consist of straight or branched 6-24 carbon chain

fatty acids or triglycerides thereof. The weight percent of the aliphatic moiety can be

10-60% with 20-40% by weight being the preferred amount.

The water dispersible and hydrophobic polyester resins of the present

invention have excellent water repellent properties as evidenced by their contact angle

measurements when used as coatings. The contact angles achieved when the resins are coated on paper are of the order of 98 or higher.

The present invention is also directed to a water dispersible and hydrophobic

polyester resin, comprising a reaction product of 30-70% by weight of a terephthalate

polymer; 5-40% by weight of a hydroxy functional compound having at least two

hydroxyl groups; 1-20% by weight of a carboxy functional compound having at least two carboxy 1 groups and 10-60% by weight of a compound selected from the group of

C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof said resin being further characterized in that the hydroxy functional compound is present at 1-3 times the

equivalents of the hydrophobic moiety. The instant invention is also directed to substrates such as paper , paperboard ,

food packaging, textiles, concrete and the like coated with a polyester resin comprising

a reaction product of 30-70% by weight of a terephthalate polymer; 5-40% by weight of a hydroxy functional compound having at least two hydroxyl groups; 1-20% by

weight of a carboxy functional compound having at least two carboxyl groups and 10-60% by weight of a hydrophobic compound selected from the group consisting of

C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof.

The present invention is also directed to an article of manufacture comprising a substrate coated with a water dispersible and hydrophobic polyester coating

composition comprising a reaction product of 40-60% by weight of polyethylene terephthalate polymer; 1 -10% by weight of neopentylglycol; 5-10% pentaerythritol; 3

to 15% by weight of trimellitic acid or trimellitic anhydride; and 10-45% by weight of

stearic acid.

The invention also features a water repellent polyester coating composition,

comprising a reaction product of 30-70% by weight of a terephthalate polymer; 5-40% by weight of a hydroxy functional compound having at least two hydroxyl groups;

1-20% by weight of a carboxy functional compound having at least two carboxyl groups

and 10-60% by weight of a hydrophobic compound selected from the group consisting of C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof. Another novel aspect of the invention is a water repellent polyester coating

composition, comprising a reaction product of 40-60% by weight of polyethylene

terephthalate polymer; 1-10% by weight of neopentylglycol; 5-10% pentaerythritol;

3 to 15 % by weight of trimellitic acid or trimellitic anhydride; and 10-45% by weight

of stearic acid.

The invention is also directed to a method for imparting water repellency to

substrates selected from the group consisting of fibrous substrates and leather comprising

applying to such susbtrates a composition comprising the reaction product of 30-70% by weight of a terephthalate polymer; 5-40% by weight of a hydroxy functional

compound having at least two hydroxyl groups; 1-20% by weight of a carboxy functional compound having at least two carboxyl groups and 10-60% by weight of a

hydrophobic compound selected from the group consisting of C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof.

This invention is further directed to a process for providing a water

repellent, separable film-like coating on the surface of a substrate comprising applying

to the substrate a water dispersible coating composition comprising a reaction product

of 30-70% by weight of a terephthalate polymer; 5-40% by weight of a hydroxy

functional compound having at least two hydroxyl groups; 1-20% by weight of a

carboxy functional compound having at least two carboxyl groups and 10-60 % by weight

of a hydrophobic compound selected from the group consisting of C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof; and curing said composition on the

substrate at a temperature sufficient to allow the cross-linking reaction of carboxylic

functionality of the polyester resin to take place; or allowing the coated surface to dry at room temperature whereby a film-like coating is provided on said surface which can

be separated from said surface as desired.

The invention also describes polyester resins which can be made containing

30 percent or more of mono-functional monomers, such as stearic acid, to provide a

much improved non-polar nature.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The objects of the present invention and many of the expected advantages

of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description.

The novel water dispersible resins of the present invention can be

represented as shown by the following structure:

~ _* - A_m

where I is the ionic group; n=l-3 defines the number of the ionic groups; P is polyester;

A is an aliphatic group; and m=3-8 represents the aliphatic group number.

There are four necessary requirements for the polyester chemistry of the

present invention:

1. A polyester backbone.

2. A multi-functional glycol in the backbone providing additional hydroxyl functionality present at 1-3 times the equivalents of group 3.

10 3. A hydrophobic moiety, such as but not limited to, a saturated fatty

acid. This moiety is present at one-third to two-thirds the equivalents of the number 2

component and must be present in total formula at 10 to 50 weight percent, the preferred level being 15-40 weight percent depending on the needed degree of water repellency.

4. An ionic moiety , either in the backbone or terminally located , present

at 5-20 weight percent, the preferred quantity being 10-15 weight percent. This moiety

can be neutralized with base if necessary to supply dispersibility in water.

There physical properties that make the resins of the present invention

unique are: 1. Hydrophobic character.

2. Ability of these resins to orient the hydrophobic groups away from

substrates to which they are applied.

3. Evidence of hydrophobic orientation as characterized by high water drop contact angles of the coated surface.

The water dispersible and hydrophobic polyester compositions of this

invention imparts desirable water and oil repellency to substrates treated therewith without adversely affecting other desirable properties of the substrate, such as soft hand

(or feeling). The composition of the present invention can be used for providing water and oil repellency to fibrous substrates such as textiles, papers, non- woven articles or

leather or to other substrates such as plastic, wood, metals, glass, stone and concrete.

The water-dispersible resins of the present invention are synthesized by

condensation polymerization with original or recycled PET or polyacid-polyalcohol

11 [multi-functional acids or alcohols] used to make polyesters along with aliphatic acids

or hydrogenated or unhydrogenated animal or vegetable triglycerides.

The water-soluble or water-dispersible resins are made from waste

terephthalate polymers, including bottles, sheet material, textile wastes and the like. The

waste terephthalate plastics may be bought from recyclers and include, but are not limited to, material identified as "PET rock". The waste terephthalate can be

characterized by the unit formula

OROoc — co n- (1)

wherein R is the residue of an aliphatic or cycloaliphatic glycol of 2-10 carbons of or

oxygenated glycol of the formula

HO (C χH₂χO )_nC χH₂χO H (2)

wherein x is an integer from 2-4 and n is 1-10.

Preferably the waste terephthalate polymer is a polyalkylene terephthalates

such as polyethylene terephthalate and polybutylene terephthalate, polycyclohexanedimethanol terephthalate or a mixture thereof. Other suitable polyester

polymers which can be used in the practice of the present invention include poly 1 ,2 and

poly 1,3 propylene terephthalate and polyethylene naphthanate. It will be understood

that, for reasons of economy, the use of waste terephthalates is preferred. However, the

12 use of virgin terephthalate resins is to be included within the scope of the disclosure and

appended claims.

The ionic group I_n needed for water-dispersibility can be a carboxylic acid which is introduced into the resin by polyacid monomers such as Trimellitic anhydride,

Trimellitic acid, or Maleic Anhydride or sulfonate groups which come from monomers such as dimethyl 5-sulfoisophthalate (DMSIP or dimethyl 5-

sulfo,l,3-benzenedicarboxylate), sulfoisophthalate ethylene glycol (SIPEG or dihydroxy ethyl 5-sulfol,3-benzenedicarboxylate, or from sulfonated alkenically

unsaturated end groups as described in Salsman Patent No. 5,281 ,630. The polyacid is

preferably selected from the group consisting of isophthalic acid, terephthalic acid,

phthalic anhydride (acid), adipic acid and etc. Other preferred polyacids but not limited

to are phthalic anhydride (acid), isophthalic and terephthalic acids, adipic acid, fumaric acid, 2,6 naphthalene dicarboxylic acid and glutaric acid. Mixtures of the above acids

and anhydrides can be used in the practice of the present invention. The weight percent

of ionic monomers in the resin is from 1 % to 20% percent, but 5 to 10% is preferred.

The backbone of the polymer is composed of polyester groups. It can be any linear or branched polyester made using polyacids and polyalcohols. The preferred

method is to generate the backbone using polyester from recycled sources. The weight

percent of the polyester backbone ingredients range from 30-80% of the whole resin,

with the most preferred being 50-60% . Such backbone is typically derived by reacting

PET such as waste PET with a hydroxy functional compound containing at least two

hydroxyl groups. The hydroxy functional compound having at least two hydroxy groups

is selected from the group consisting of ethylene glycol, diethylene glycol, triethylene

13 glycol, cyclohexanedunethanol, propylene glycol, 1,2-propylene glycol, 1,3-propane

diol, 1,2-butylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol,

1,5-pentanediol, 1,6-hexanediol, glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, erythritol or a monosaccharide. In another embodiment, other hydroxy

compounds having at least two hydroxyl groups include derivatives of glycerol, trimethylolpropane, trimethylolethane, pentaerythritol, erythritol or a monosaccharide

oxyalkylated with 5-30 moles of ethylene oxide, propylene oxide or a mixture thereof,

per hydroxyl of the hydroxy functional compound.

The aliphatic groups consist of 6-24 carbon chain fatty acids or triglycerides

thereof such as stearic, oleic, palmitic, lauric, linoleic, linolenic, behenic acid or their

mixtures. These can come from hydrogenated or unhydrogenated animal or vegetable

oil, such as beef tallow, lard, corn oil, soy bean oil, etc. , etc. If highly unsaturated fatty

acids or triglycerides are used care must be taken to prevent cross-linking through the

unsaturated group. The weight percent of the aliphatic moiety can be 10-60% with 20-40% the preferred amount.

There are two basic routes to the manufacture of these resins. These routes are outlined below:

Route 1

(1) Aliphatic Acids or Esters + Multifunctional Glycol ^→ esterification or transesterification = Hydrophobic Glycol

(2) Hydrophobic Glycol + PET (or Diacid with Dialcohol) esterification —

or transesterification = Hydrophobic Polyester

14 (3) Hydrophobic Polyester + Ionic monomer → esterification or transesterifcation = Water Dispersible and Hydrophobic Polyester Resin

Route 2 (1) Diacid or PET + Multifunctional Glycol → esterification or transesterification = grafting polyester with hydroxyl groups throughout chain and/or

as end groups

(2) Grafting polyester + Aliphatic Acids or Esters — > esterification or

transesterification = Hydrophobic Polyester Resin

(3) Hydrophobic Polyester + ionic monomer — - > esterification or

transesterification = Water Dispersible and Hydrophobic Polyester Resin

The following steps are used in the process to produce the resin of the

present invention:

1. Incorporation of a non-polar group or groups which can be chosen from the following: fatty acids of the type stearic acid, behenic acid, palmitic acid, lauric

acid, oleic acid, linoleic acid, etc.; triglycerides from animal or vegetable sources of the

type beef tallow, corn oil, soybean oil, peanut oil, safflower oil, hydrogenated versions

of these , etc . ; reactive silicones , blown paraffins or mineral oils , hydrophobic urethanes ,

etc. This group must be present at 10-50 weight percent.

2. Incorporation by esterification or transesterification of a multi¬

functional hydroxyl component or components such as pentaerythritol, sorbitol, glycerol,

15 etc. at levels consistent with but not limited to 1 to 3 times the reactive equivalent of

components from group 1.

3. Esterification or transesterification of ingredients typical of those used

to make polyester polymers. These ingredients can be chosen from Polyethylene

Terephthalate or similar terephthalates and/or difunctional acids such as terephthalic acid, isophthalic acid, phthalic acid or anhydride combined with difunctional alcohols

such as ethylene glycol, diethylene glycol, neopentyl glycol, propylene glycol, etc.

4. Incorporation of a ionic group or groups needed for dispersing the

resin in water. Examples of these groups are trimellitic anhydride, maleic anhydride,

sulfo succinate, sulfonated isophthalic acid or its esters, etc.

5. Dispersing the resin in water containing an amount of base, if

needed, to neutralize the pendant acid groups.

In practicing the process of the present invention, steps 1-3 can be done in

any order but the preferred process embodiment order is as listed above.

The polyester resins are usually and preferably made using an ester-interchange catalyst. These catalysts are metal carboxylates and well known

organometallic compounds, particularly compounds of tin or titanium. Preferred

catalysts include manganese acetate, sodium acetate, zinc acetate, cobalt acetate or

calcium acetate, tetraalkyl titanates, in which the alkyl is of up to 8 carbon atoms, as

well as alkyl stannoic acid or dialkyl tin oxides, such as monobutyl stannic acid or

dialkyl tin oxide. Preferred catalysts include monobutyl stannoic acid and tetrapropyl

or tetrabutyl titanate, or a mixture thereof.

16 The resulting resinous products obtained are generally taken up in relatively

concentrated aqueous solutions of alkali metal or ammonium hydroxides or carbonates. The concentration employed can be determined by routine experimentation. However,

if shipping of the concentrated aqueous solutions to a point of use is contemplated, it is

preferred to produce highly concentrated solutions. It is within the scope of this invention to produce initial solutions or dispersions, containing 20-30% or more of resin

solids.

The resins of the present invention typically have average molecular weights

in the range of 3000 to as high as 50,000. Preferred resins typically have a molecular

weight of about 4000 to about 8000. Of course the intended end use will determine which molecular weight will be optimum. The average molecular weight of the resins

is typically determined by GPC or by viscosity measurements or other methods well known in the art of polymer chemistry.

The instant process for providing a water dispersible polyester coating composition on the surface of substrates is accompanied by a cross-linking reaction

within the polyester resin itself or with hydroxyl groups from a number of other sources

such as the surfaces of cellulosic substrates. The coating can be applied at any

temperature and allowed to dry even at room temperature with sufficient time.

Preferably the substrates coated with the present polyester coating composition are

heated at the temperature that water can be removed, thereby the equilibrium of the

cross-linking reaction will be shifted to cure the polyester coating on the surfaces of

substrates. Said temperature is preferably above 100 degrees Centigrade, more

preferably above 130 degrees Centigrade.

17 Another important factor that could affect the cross-linking reaction of carboxylic functionality of the instant polyester resin on the substrates is the hydroxyl

content of the surfaces of the substrates coated therewith. The large amount of

hydroxyls on the surfaces will favor the equilibrium shift and cause the cross-linking reaction to take place more rapidly. Therefore, the materials having more free hydroxyl

groups on their surfaces are preferably used as substrates to be coated of this invention.

For example, cellulosic materials, e.g. paper or paperboard. The substrates can be a

fabric such as a non-woven, woven, knit or scrim; fiber or polymeric film. The fabric,

fiber or film can be made of polymeric materials, such as polyamide, polyester,

polyvinylidene fluoride, poly aery lie, poly olef ins such as polyethylene and

polypropylene. Exemplification include; for example, fiber weaves, glass, paper, wood,

leather, fur, brick, concrete, metal, ceramics, plastics. Examples of manufactured fiber weaves include cotton, flax, wool, silk, and other plant and animal natural fibers. Examples also include synthetics, such as polyamide, polyester, poly vinyl alcohol,

poly aery lonitr ile, poly vinyl chloride, polypropylene, rayon, acetate, semi-synthetic fibers, glass fibers, asbestos fibers, and other inorganic fibers.

The water dispersible polyester coating composition of this invention is

especially useful for the production of packaging materials because the coatings have

very good barrier properties and exhibit improved water and oil resistance.

The water dispersible polyester coating composition can be used directly for

coating. The polymer dispersion may be applied to a substrate film or sheet on a coating

apparatus. Another possible method for applying the coating to the substrate film or

sheet is by the reverse gravure process. In order further to improve the adhesion to the film or sheet, the substrate film or sheet may be subjected beforehand to flaming-off treatment to remove any protruding portions on the surfaces of substrates.

By means of the process described, it is possible in a simple manner to

produce water- and moisture-impermeable coatings, for example on packaging paper or

paperboard.

EXAMPLES

The following examples are set forth for the purpose of illustrating the

invention in more detail. The examples are intended to be illustrative and should not be

construed as limiting the invention in any way. All parts, ratios, percentage, etc. in the examples and the rest of the specification, are by weight unless otherwise noted.

Throughout all the Examples described below, a 1000 mL four-neck flask reactor suitable for high temperature cooking is used for the reactions. The flask is

equipped with a condenser, a nitrogen inlet, a thermometer, and a stirrer. The

chemicals and their ratio are listed as shown in the following examples:

EXAMPLE 1

Ingredients Wt% Grams

Recycled PET 56.29 598.8

Pentaerythritol 6.71 71.4

Neopentyl Glycol 2.6 27.7

Tetra Propyl 0.08 0.8 Titanate(TPT)

Stearic Acid 28.24 300.4

Monobutyl Stannic Acid 0.08 0.9

Trimellitic Anhydride 6 63.8

19 The PET, pentaerythritol, neopentyl glycol, and the TPT are added into reactor and heated to 200-270 °C under a nitrogen blanket. The transesterification reaction takes 30 to 180 minutes and is monitored by the presence of a clear pill. Then stearic acid and

monobutyl stannoic acid are added and reacted until the acid value is less than 10. Then Trimellitic Anhydride is added and reacted in at 160-180 degrees Centigrade for thirty

minutes. The whole reaction will last for 5 to 12 hours. The obtained resin is dispersed

in dilute ammonium solution. The amount of the ammonium hydroxide used depends

on the final dispersed resin pH. Using this method a white dispersion or emulsion of

the resin is obtained.

Using this solution with or without clay and with or without dye to coat

paper or paperboard, a glossy and water repelling surface finish on the paper or paperboard is obtained. The strength of the coated paper or paperboard is increased as well. When the coated paper or paperboard is pulped (stirred vigorously) in a diluted

sodium hydroxide solution at room temperature or higher, the resin is removed and

redispersed and the paper is repulped nicely.

EXAMPLE 2

Inαredients Wt% Grams

Recycled PET 56.29 598.8

Pentaerythritol 6.71 71.4

Neopentyl Glycol 2.6 27.7

Tetra Propyl 0.08 0.8 Titanate(TPT)

Oleic Acid/stearic 28.24 300.4 acid

Monobutyl Stannic 0.08 0.9 Acid

Maleic anhydride 6.00 63.83

20 The PET, pentaerythritol, neopentyl glycol, and the TPT are added into reactor and heated to 200-270 ° C under a nitrogen blanket. The reaction takes 30 to 180 minutes and

is monitored by the presence of a clear pill. Then stearic acid and monobutyl stannoic acid are added and the whole is esterified until the acid value is less than 10. Maleic

anhydride is added and reacted at 150-180 degrees Centigrade for 15 minutes. The

whole reaction will take 5 to 12 hours. The final resin is poured into a sodium sulfite

solution in which the amount of sodium sulfite is at same mole ratio, or slightly less than

the maleic anhydride. Using this method a white dispersion or emulsion of the resin is

obtained. The water-dispersed resin is coated on the paper and paperboard, which leads to the same results as Example 1.

EXAMPLE 3

A recipe containing a triglyceride is shown as follows:

Inαredients Weiαht % Grams

Recycled PET 48.80 480

Pentaerythritol 6.83 67.17

Neopentyl Glycol(NPG) 2.65 26.04

Tetra Propyl Titanate(TPT) 0.08 0.8

Hydrogenated Tallow 24.98 245.7

Monobutyl Stannic Acid 0.08 0.8

Trimellitic Anhydride or 9.83 96.67 Maleic Anhydride

Isophthalic acid 6.76 66.45

The hydrogenated tallow triglycerides are first reacted with pentaerythritol at 180 to 270

degrees Centigrade, then PET, NPG, and TPT are added to the reactor and

transesterified with the alcoholized triglyceride. Isophthalic Acid or Phthalic Acid is

2 1 then added to increase the resin molecular weight. Finally Trimellitic Anhydride or Maleic Anhydride is reacted in to provide a neutralizable end group. With this formula

other polyalcohols and polyacids can be used as well. The final resin is diluted in

ammonium or sodium sulfite solution at 50 to 90 degrees Centigrade. The final

water-dispersed resin is a stable emulsion. The coated paper or paperboard 's surface

exhibits the same water repellant properties as the previous examples. The board is

easily repulped and the coated paper's printing holdout, strength, gloss, and other

properties are much improved.

EXAMPLE 4

In this example the same formula is used as in Example 3 except the hydrogenated tallow triglycerides are substituted with corn oil or soy-bean oil. Care

must be taken to prevent cross-linking reactions from occurring. The resin properties

are similar to those of Example 3 except that the presence of unsaturated groups in the oil makes the resin less firm. The coating on paper or paperboard has a slightly higher

gloss than those produced with hydrogenated triglycerides.

EXAMPLE 5

The formula is shown as follows:

22 Inαredients Weiαht% Grams

Pentaerythritol(PE) 7.07 67.7

Neopentyl Glycol 19.18 182.26

Diethylene Glycol 3.35 31.84

Stearic Acid 24.98 245.7

Monobutyl Stannic Acid 0.1 0.96

Trimellitic 10.17 96.67

Anhydride(TMA) or Maleic Anhydride(MA)

Isophthalic acid 34.27 325.64

The Stearic acid, the Monobutyl Stannoic Acid, and the Pentaerythritol are added to the

vessel and reacted at 160 to 270°C until the acid value is less than 100. The Isophthalic

acid, the Neopentyl Glycol, and the Diethylene Glycol are added to reactor and the

polymerization is continued until the acid value is below 10. Finally the TMA or MA is added at a reduced temperature to ensure control. The final resin is dispersed in ammonium or sodium sulfite solution as in previous examples. The resin dispersion has

the appearance of a stable emulsion. The coated paper or paperboard shows great water

repelling properties. The gloss also is increased for coated papers.

EXAMPLE 6

The same formula is used as in Example 5 except the Isophthalic acid is

replaced with Terephthalic acid with the same results.

EXAMPLE 7

The same formula is used as in Example 5 except the Isophthalic is replaced

with Phthalic acid with similar results.

23 EXAMPLE 8

The formula is shown as follows:

Inqredients Weiαht% Grams

Pentaerythritol(PE) 7.07 67.7

Neopentyl Glycol 19.18 182.26

Diethylene Glycol 3.35 31.84

Stearic Acid 24.98 245.7

Monobutyl Stannic Acid 0.1 0.96

Trimellitic 10.17 96.67

Anhydride(TMA) or Maleic Anhydhde(MA)

Phthalic acid 34.27 325.64

The Stearic acid, the Monobutyl Stannoic Acid, and the Pentaerythritol are added to the vessel and reacted at 160 to 270 °C until the acid value is less than 100. The Phthalic

acid, the Neopentyl Glycol, and the Diethylene Glycol are added to reactor and the

polymerization is continued until the acid value is below 10. Finally the TMA or MA

is added at a reduced temperature to ensure control. The final resin is dispersed in ammonium or sodium sulfite solution as in previous examples. The resin dispersion has

the appearance of a stable emulsion. The coated paper or paperboard shows great water

repelling properties. The gloss also is increased for coated papers.

EXAMPLE 9

The same formula is use as in Example 5 except the TMA or MA is replaced

with DMSIP or SIPEG and reacted as a polyacid or poly alcohol. A good

water-dispersible resin is obtained and the resin shows similar properties as described above.

24 The novel water dispersible and hydrophobic polyester resins of the present

invention can be used to coat substrates such as cellulosic or synthetic substrates such

as paper. More in particular, the polyester resins find use as coatings in the following industrial applications:

I. PAPER Because these resins contain a high concentration of hydrophobic groups and have a much improved ability to orient those hydrophobic groups away from the paper

or paperboard, the surface of paper or paperboard coated with these resins shows an

amazing water repelling effect. This water repelling effect produces surfaces that have higher water drop contact angles than other currently used resins. Therefore these resins

can effectively make the paper or paperboard surface waterproof or water repellent at

much lower concentrations than other commonly used resins. In addition the resins

described here can be easily removed from the paper, paperboard, or other substrate by

washing with water that has been made basic by the addition of ammonium hydroxide,

sodium hydroxide, or other commonly used basic additives. The advantages for using

these resins in the paper and paperboard industry are threefold. One advantage is in the

use of lesser amounts of materials on the paper of paperboard, a second advantage is the

recycling of waste PET (possibly from bottle sources) back into packaging materials, and the third advantage is that all materials coated in this manner can be easily repulped and therefore recycled. In connection with paper coating applications, the following are particularly preferred:

25 A. Paper or paperboard for food packaging

Some food packages (fresh produce, frozen goods, dry food, dairy products,

etc.) need high hydrophobic properties of the package box surface to ensure package

shelf-life under high moisture conditions. In addition to plastic packages, coated paper

or paperboard is commonly used. The coating on this paper or paperboard is generally very hydrophobic. The resins most widely used in paper or paperboard coatings are the

mixture of polyethylene vinyl acetate copolymers (usually referred to as EVA for

ethylene vinyl acetate) in combination with paraffin wax. This type of coating system

produces hydrophobic coatings which are water insoluble and therefore very difficult to remove from the paper or paperboard during repulping. This difficulty in repulping

inhibits easy recycling of these paper products. The resins described in this invention

are easily repulsed using basic additives as described above.

The resins described in this invention are composed of raw materials that

have a reputation of being generally regarded as safe and non-toxic. This fact along

with the great need for water repellent coatings in the paper industry for food packaging

etc., and the inexpensive nature of these resins which may be produced from recycled

PET, make these resins highly desirable for coating paper or paperboard intended for

food packaging.

In the Frozen Food Industry paper containers are used to store food for use

in instant cooking, microwave ovens. These containers must be moisture resistant to handle the freezing and thawing conditions they are subjected to. The disclosed resins,

because of their FDA status for food contact, would be ideal candidates for the

protection of these paper containers.

26 B. Printing Paper

Paper intended for printing or magazine paper has a coating that consists of Styrene Butadiene Rubber latex (SBR), poly vinyl acetate latex, rosin and/or other

materials such as clay and starch. The coating is used to impart properties such as

surface smoothness, strength, gloss, ink holdout, and water resistance. The new resins

disclosed in this patent can also be used to impart these properties at lower coating

weights. For example printing paper coated with these resins alone have excellent water repellency and ink holdout as well as increased strength and gloss.

C. Paper or Paperboard for storage or transport

Paper Bags for carrying consumer purchases, etc. have a problem in that if

they get wet they lose their strength and tear easily. Making these bags water repellent

or just water resistant would help solve this problem. Letters, envelopes, and courier packages need waterproofing to keep the contents dry during mailing or shipping.

Envelopes or packaging board coated with these disclosed resins provide sufficient protection.

D. Release Paper

Release coatings are used where an adhesive material needs to hold to a surface but not so much that it tears the surface when pulled from it. Currently silicones

are used for this purpose. The resins described here can be used for this purpose as well

since the hydrophobic properties make them ideally suited as adhesive release agents.

27 E. Miscellaneous Paper Items

Other paper products which could benefit from an inexpensive waterproofing

system would be fiber drums, book and notebook covers, popcorn bags, paper plates, paper cups, paper rainwear such as disposable clothing, paper construction materials

(wallpaper, dry wall, sound board, or concrete construction forms), and any other outdoor use paper product that could be damaged by rain, rainwater, or high moisture

conditions.

II. TEXTILES In the textile industry there are several needs for waterproofing or water

resistant finishes. The currently used resins can be expensive and difficult to apply.

The resins described here can find applications in a number of areas in the textile industry. Some of these areas of application include: Fiber or Thread Finishes, clothing

or apparel in general, tarps, rainwear, non-wovens, nylon microdenier fabrics, bedding,

mail bags, re-application of waterproofing agents and footwear.

III. WOOD

Wood products especially those used in outdoor applications, need to be

protected from rain and weather. The resins described here can be used to waterproof

wood products. Some examples of wood products where the described resins could be

applied are: furniture, wood decks, construction lumber, plywood, wood for concrete

molds, siding for houses, telephone poles, roofing tiles, paneling for interior walls,

wooden crates and boxes for shipping and storing, and wooden boats or boat parts.

28 IV. CONCRETE

It is desirable in some concrete applications for there to be a sealer or water resistant finish applied to the concrete after it has set. This finish provides increased

durability and longer life of the concrete surface as well as allowing rain water to run off more effectively. The products described in this invention can be used for this purpose. Some examples are: overpasses and bridges on roads, high traffic areas such

as stadium decks, etc., outdoor stadium seats, driveways, roadways and concrete

housing.

V. PAINT

In some instances it is desirable for a paint (or protective coating) to exhibit

a certain amount of water repellency. Some examples are: Traffic Paint to replace

currently used solvent based alkyd resins and general purpose Latex. In the case of the

latex, the inventive resins can be used as additives.

VI. LEATHER Leather products can be treated for water repellency. Here the added gloss would also be desirable. Typical leather products include shoes, handbags, coats and

gloves.

VII. INKS In the ink market resins are used to adhere the ink to some substrate. Once

dry they must be moisture and abrasion resistant. Many currently used resins are water

29 based. The described resins here would make ideal candidates as ink resins or additives since the resins are very adhesive, especially to cellulosics, and once dry would be very

water resistant.

VIII. GLASS

Fiberglass is used as the structural material for a great deal of commonly used items such as shower stalls, boats, kitchen and bathroom sinks. The described

resin could be used as part of the formulation to make these products repel water more

effectively. The dispersions of this invention could also be used to treat the glass fibers

themselves, as in sizing, for greater water repellency or greater resin solubility.

IX. METAL COATINGS

Metal coils are commonly coated with a resin to prevent rust or oxidation

caused by moisture in the air. The currently used products are generally resins dissolved in some solvent. The resins described here could be used as replacements for

these coatings. Cars, gutters and appliances may be coated with the resins of the present

invention.

The amount of the composition applied to a substrate in accordance with the present invention is chosen so that sufficiently high or desirable water and oil

repellencies are imparted to the substrate surface, said amount usually being such that

0.01 % to 10% by weight, preferably 0.05 to 5% by weight, based on the weight of the

substrate, of polyester is present on the treated substrate. The amount which is

30 sufficient to impart desired repellency can be determined empirically and can be increased as necessary or desired.

The treatment of fibrous substrates using the water and oil repellency

imparting composition of the present invention is carried out by using well-known methods including dipping, spraying, padding, knife coating, and roll coating. Drying

of the substrate is done at 120°C or below, including room temperature, e.g., about

20 °C with optionally heat-treating the textile products in the same manner as in

conventional textile processing methods.

The effectiveness of the coatings resulting from the resins of the present

invention is illustrated in Example 10.

EXAMPLE 10 Contact Angle Comparisons

The following example illustrates the effectiveness of applicant's polyester

resins as water repellent coatings for paper or paperboard. The test was performed using a Kernco Model G-I Contact Angle Goniometer used to measure the contact angles

between the surface of a piece of paper or paperboard and a drop of distilled water

placed on the paper.

PROCEDURE

A 0.1 ml sample of distilled water was place on the surface of a piece of

uncoated (control) and coated paperboard using a micro syringe. The initial angle of the

drop to the paperboard surface was taken. A time of 5 minutes was allowed to elapse

3 1 and a second contact angle was taken. The test was performed ten times and the average

values calculated. The difference between the two average values was calculated as the

Lose of Angle.

RESULTS

The following chart reflects the results using uncoated paper and various

coating formulas.

TEST SAMPLE Initial 5 min. Lose of Angle Angle Angle

Control: No coating 78.2 64.3 13.9

Graphsize: polyurethane size 91.3 84.4 6.9

PE-230: Hydrophilic polyester size 68.5 52.7 15.8

LB-100(30%): Eastman polyester 68.0 53.3 14.7

Styrene Maleic Polymer 95.0 77.7 17.3

2161: XWP with 43.17% Fatty acid 110.3 N/D N/D

2160: XWP with 37.94% Fatty acid 112.0 103.8 8.2

2148: XWP with 28.82% Fatty acid 107.5 N/D N/D

2141 : XWP with 25.86% Fatty acid 104.3 96.6 7.7

2180: XWP with 20.00% Fatty acid 102.0 94.3 7.7

2086: XWP with 15.00% Fatty acid 98.8 81.0 17.8

In the table above, the resin compositions of the invention are defined as

follows:

Resin 2161: This resin is the reaction product of: 38.57 wt% PET, 43.17 wt% fatty

acid (6.50 wt% stearic; 10.22 wt% oleic and 26.45 wt% hydrogenated tallow glyceride),

8.10 wt% pentaerythritol and 10 wt% trimellitic anhydride.

32 Resin 2160: This resin is the reaction product of: 42.84 wt% PET, 37.94 wt% fatty

acid (18.97 wt% stearic and 18.97 wt% hydrogenated tallow glyceride), 9.08 wt% pentaerythritol and 9.96 wt% trimellitic anhydride.

Resin 2148: This resin is the reaction product of: 48.08 wt% PET, 28.82 wt% fatty

acid (14.41 wt% stearic acid and 14.41 wt% soybean oil), 6.89 wt% pentaerythritol, 2.58 wt% neopentylglycol, 9.96 wt% trimellitic anhydride and 3.68 wt% isophthalic

acid.

Resin 2141 : This resin is the reaction product of: 34.27 wt% isophthalic acid, 25.86

wt% stearic acid, 7.07 wt% pentaerythritol, 19.18 wt% neopentylglycol, 3.35 wt% diethyelenglycol and 10.17 wt% trimellitic anhydride.

Resin 2180: This resin is the reaction product of: 61.72 wt% PET, 20.00 wt% stearic

acid , 4.75 wt % pentaerythritol , 2.46 wt % neopentylglycol , 0.91 wt % diethyleneglycol ,

10.00 wt% trimellitic anhydride.

Resin 2086: This resin is the reaction product of: 74.90 wt% PET, 15.00 wt% stearic

acid, 4.50 wt% pentaerythritol, 3.47 wt% neopentylglycol, 1.96 wt% diethyleneglycol.

The physical properties that make this resin unique are:

1. Hydrophobic character.

33 2. Ability of these resins to orient the hydrophobic groups away from substrates to which they are applied.

3. Evidence of hydrophobic orientation as characterized by high water drop contact angles of the coated surface.

EXAMPLE 11

Coating Process

First, a paper sheet was electrically pretreated (Corona treatment) on a pilot

plant. In the second step, the corona-treated paper sheet was coated with XWP (resin

2141, with 25.86% fatty acid) by using conventional coating techniques in the art, e.g. roll coating. In the third step, the coated paper sheet was dried at 120°C or below by

supplying IR heat drying unit. The sheet coated in this manner was wound up.

It will be apparent from the foregoing that many other variations and

modifications may be made regarding the hydrophobic polyester resins described herein,

without departing substantially from the essential features and concepts of the present

invention. Accordingly, it should be clearly understood that the forms of the inventions

described herein are exemplary only and are not intended as limitations on the scope of the present invention as defined in the appended claims.

34

Claims

What is claimed is:

1. A process for providing a water repellent, separable film-like coating

on the surface of a substrate comprising the steps of:

(a) applying to the substrate a water dispersible coating composition

comprising a reaction product of 30-70% by weight of a terephthalate polymer; 5-40% by weight of a hydroxy functional compound having at least two hydroxyl groups;

1-20% by weight of a carboxy functional compound having at least two carboxyl groups

and 10-60% by weight of a hydrophobic compound selected from the group consisting

of C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof; and,

(b) curing said composition on the substrate at a temperature sufficient to allow the cross-linking reaction of carboxylic functionality of the polyester resin to

take place; or,

(c) allowing the coated surface to dry at room temperature whereby a film-like coating is provided on said surface which can be separated from said surface

as desired.

2. The process as claimed in claim 1, wherein in step (b) the

temperature is greater than 100 ┬░C.

3. The process as claimed in claim 2, wherein the temperature is greater

than 130┬░C.

4. The process as claimed in claim 1, further comprising the step of:

(d) providing a substrate having at least one surface to be coated, said

surface having high hydroxyl content, thereby speeding up the cross-linking reaction.

35

5. The process as claimed in claim 4, wherein the substrate is a fabric

or a fiber.

6. The process as claimed in claim 5, wherein the substrate is selected from the group consisting of non- woven materials, woven materials, knits, scrim, paper,

wood, glass, leather, cotton, flax, wool, silk, and other plant and animal natural fibers.

7. A process for the production of a cellulosic article coated with a

water repellent coating composition which allows the cellulosic article to be recycled

comprising the steps of:

(a) providing a recyclable cellulosic substrate having at least one surface

to be coated;

(b) coating said surface with a water dispersible coating composition

comprising a reaction product of 30-70% by weight of a terephthalate polymer; 5-40% by weight of a hydroxy functional compound having at least two hydroxyl groups;

1-20% by weight of a carboxy functional compound having at least two carboxyl groups

and 10-60% by weight of a hydrophobic compound selected from the group consisting

of C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof;

(c) curing said coating composition on the cellulosic article surface at a temperature sufficient to allow the cross-linking reaction of carboxylic functionality of

the polyester resin with hydroxyl functionality of the cellulosic article surface to take

place; or,

(d) allowing the coated cellulosic article surface to dry at room

temperature; and thereby,

36 (e) forming an integral film on said surface from said coating, said film being separable from said surface to permit recycling of the cellulosic substrate.

8. The process as claimed in claim 7, wherein the cellulosic substrate is paper or paperboard.

9. The process as claimed in claim 7, wherein in the step (c) the

temperature is greater than 100 ┬░C.

10. The process as claimed in claim 9, wherein the temperature is greater

than 130┬░C.

11. Cellulosic article prepared by a process as claimed in claim 7.

12. A process for the production of packaging materials, which comprises

the steps of:

(a) providing substrate suitable for packaging having at least one surface

to be coated;

(b) coating said surface with a water repellent coating composition

comprising a reaction product of 30-70 % by weight of a terephthalate polymer ; 5-40 %

by weight of a hydroxy functional compound having at least two hydroxyl groups;

1-20% by weight of a carboxy functional compound having at least two carboxyl groups

and 10-60% by weight of a hydrophobic compound selected from the group consisting

of C₆-C₂₄ straight chain or branched fatty acid or triglycerides thereof;

(c) curing said coating composition on the surface at a temperature

sufficient to allow the cross-linking reaction of carboxylic functionality of the polyester

resin to take place, whereby coated packaging materials are obtained.

37

13. The process as claimed in claim 12, wherein the minimum coating film formation temperature of said polyester resin composition is greater than 100┬░C.

14. The process as claimed in claim 13, wherein the temperature is greater than 130┬░C.

5 15. The process as claimed in claim 12, wherein the substrates suitable for packaging are paper plastic films or metal foils.

16. Packaging material prepared by a process as claimed in claim 12.

17. A process for the production of packaging materials , which comprises

the steps of: o (a) providing substrate suitable for packaging having at least one surface

to be coated;

(b) coating said surface with a water repellent coating composition

comprising a water dispersible and hydrophobic polyester resin having the formula:

5 In - P - A_m

wherein I is an ionic group; n= l-3 is the number of ionic groups; P is a polyester

backbone; A is a fatty aliphatic group; m=3-8 is the number of fatty aliphatic groups

and wherein I is present in amount of from about 1 % to 20% by weight; the polyester

0 backbone is present in an amount of from about 30% to 80% by weight and the fatty

aliphatic group is present in an amount of about 10% to 60% by weight; said polyester resins exhibiting high water repellency as shown by an initial contact angle of at least

38 98 when a drop of water is applied to the surface of said cellulosic substrate which has been coated with said resin.

(c) curing said coating composition on the surface at a temperature

sufficient to allow the cross-linking reaction of carboxylic functionality of the polyester

resin to take place, whereby coated packaging materials are obtained.

39