DE2325087A1 - IMPROVEMENT OF THE ADHESION OF HYDROPHILIC LAYERS ON DIMENSIONAL POLYESTER FILM CARRIERS - Google Patents

Description

AGFA-GEVAERT AKTIENGESELLSCHAFT

LEVERKUSEN

May 16, 1973

Improvement of the adhesion of hydrophilic layers on mass- containing polyester film supports

O ·

This invention relates to a method of improvement the adhesion of hydrophilic layers to dimensionally stable polyester film supports and in particular to a method for Improvement of the adhesion of hydrophilic, photographic layers on films made of dimensionally stable polyethylene terephthalate and composite films and photographic materials obtained thereby.

To ensure complete adhesion of hydrophilic layers such as photographic light-sensitive emulsion layers ensure dimensionally stable polyester film supports, i.e. polyester films that are biaxially stretched and thermoset, it is known to place several intermediate layers between the support and the photosensitive emulsion layer. In the in most cases two intermediate layers are required. A first layer, the substrate layer, shows good adhesion on the polyester film and at the same time has good adhesion properties with regard to the second layer, the adhesive layer, which is usually largely formed from a hydrophilic colloid such as gelatin.

It is known that the adhesion of the substrate layer to the Polyester film base can be promoted by various means, which can be used individually or in combination:

- Use of chlorine-containing copolymers as binders for the substrate layer;

- Applying the substrate layer before stretching and the

Heat curing of the polyester film carrier, the ^ last-A-G 1133

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re is carried out at a temperature of about 200 C;

- addition of compounds to the casting composition; it - ^ are generally organic solvents, which attack the surface of the polyester film. .

Although such a substrate layer itself adheres very tenaciously to a dimensionally stable polyester film support, it is still one additional adhesive layer required. In fact, it can be said that the adhesion of a photographic, gelatin-containing Layer directly on the hydrophobic substrate layer much too leaves something to be desired. This confirms the general rule that a gelatin layer adheres well to a hydrophobic one Film surface can only be obtained if the surface of the hydrophobic film is provided with an adhesive layer which contains a sufficient amount of gelatin.

The subject of the present invention is a single substrate layer, which have the properties of the usual two-layer adhesive combination united in itself. In this single layer, chlorine-containing copolymers are present as binders, so that complete adhesion to the polyester film support is obtained. Furthermore, the single substrate layer contains a sufficient one Amount of gelatin, so that photographic emulsion layers, that contain gelatin also adhere quickly to the substrate layer.

As mentioned above, the adhesion of the substrate layer can be improved on the Polyesterfilmträger.stets, .if it heats the carrier and the substrate layer together to a temperature of about 200 ⁰ C. In practice, this can only be done if the substrate layer is applied after the polyester film has been stretched longitudinally. The thus coated polyester film is then stretched in the transverse direction to the desired dimension and the heat curing is carried out at einer.Temperatur of about 200 ⁰ C., while the film under

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Tension holds. ■

It is also known that a polymeric or a low molecular weight product can only be stretched if the temperature during the stretching is higher than the softening point of the polymer or the low molecular weight product. The 'stretching polyester film usually happens when ■ about 80 C. Since gelatin has an unmeasurable softening point, l \ jb it impossible to stretch a dry gelatin layer at this temperature of 80 ⁰ C "If a layer, consisting only of a mixture consists of gelatin and a chlorine-containing copolymer, is stretched, veiled layers are always formed. This can only be attributed to the fact that the miscibility of gelatin and the chlorine-containing polymer is insufficient to achieve

Λ.

ensure that the presence of the stretchable polymer has a beneficial effect on the stretchability of the gelatin.

Another object of the invention is hydrophilic. layers in general and photographic layers containing gelatin

in particular to create. which are based on a dimensionally stable poly- • ester film by using a single substrate layer, which is a mixture of gelatin and a chlorine-containing copolymer contains, adhere well. . . . ■

Another object of the invention is to improve the adhesion of the substrate layer to the polyester film support by heating both to 180 ° -220 ° C. Another subject matter is the use of additives in the coating composition of the substrate layer so that the polyester film support carrying the substrate layer can be stretched to a sufficiently high degree and thermoset at 180-220 C to obtain a dimensionally stable polyester film, its substrate layer remains perfectly clear during stretching and heat setting. ^f

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A method has now been found to improve the adhesion of hydrophilic layers to a dimensionally stable polyester film carrier, the method comprising the following steps: after longitudinal stretching of the polyester film carrier, application of a single substrate layer, stretching of the polyester film carrier coated in this way in the transverse direction and heat curing 180-220 ⁰ C. the substrate layer contains 30 to 80 wt .-% of a chlorine-containing copolymer, 5 to 30 wt .-% gelatin, 5 to 40 wt -.% of a plasticiser for the gelatin, according to the following definition and 0 to 30 weight .-% of a metal complexing antistatic agent.

Understood by table makers for gelatin according to the invention one compounds which are soluble or dispersible in water and photographically inert and have the property of -layers, those made from mixtures of gelatin and chlorine-containing polymers are formed to make them stretchable, these layers after being stretched and heated to relatively high temperatures remain completely transparent. The effectiveness of these so-called plasticizers is not based solely on the known ones Effects of external plasticizers, such as those in "Plasticization and Plasticizer Processes", Advances in Chemistry, Series 48 - American Chemical Society, Washington D.C, 1965, to be discribed. The plasticizers are also likely to have an improvement in the miscibility between gelatin and chlorine-containing copolymer result, so that actually the chlorine-containing copolymer as an external plasticizer for gelatin serves.

Suitable plasticizers are aliphatic ^ polyhydroxy compounds, such as glycerine, tri (/ I-hydroxyethyl) glycerine, 1,1,1-tri (hydroxymethyl) propane, 2-N "itro-2-ethyl-1,3-propanediol, 1,3-dichloro-2-propanol, 1,2,4-butanetriol, 3 ~ hydroxymethyl-2,4, -dihydroxypentane, 1,2,6-hexanetriol, 2-hydroxymethyl-4-hydroxyamyl alcohol, "Gly.perinaldehyd and mannitol. "

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Also suitable compounds are caprolactam and N, N ¹ -Dimethylha ( "p.stoff Other suitable are aliphatic .Weichmacher ^ carboxylic or sulfonic acids, such as glutaric acid, adipic acid, azelaic;. Acid, sebacic acid, mono- and dichloroacetic acid, 1,2 , 3-propene. Tricarboxylic acid, acrylic acid, methacrylic acid, maleic acid, fumaric acid, itaconic acid and 2-sulfoethyl methacrylate; furthermore aromatic acids, such as phthalic acid, o-sulfobenzoic acid, o-nitrobenzoic acid, o-aminobenzoic acid, p-hydroxybenzoic acid. And Salicylic acid.

The chlorine-containing copolymers of the substrate layer .are copolymers containing 70 to 95 wt -.% Of vinyl chloride and / or

Vinylidene chloride, 0.5 to 10% by weight of a hydrophilic monomer and 0.5 "to 25% by weight of at least one other blend polynizable Contain monomers.

Acrylic acid esters can be used as copolymerizable monomers or methacrylic acid can be used, such as methyl, ethyl, * butyl, hydroxyethyl, hydroxypropyl, glycidyl and cyanoethyl acrylate or methacrylate; continue to vinyl esters such as vinyl acetate and the vinyl ester of versatic acid available from Shell Chemical Co. is traded under the trade name VEOVA 10 and a branched vinyl carboxylic acid ester with a molecular weight of and corresponds to the following formula:

CH ₀ = CH-O-CO-C-

where E> j., Eg "^ ²¹⁰ · ^E x represent alkyl groups which together have 7 to 9 carbon atoms and
represents a methyl group.

9 carbon atoms and wherein only one of R ^, R ₀ and

Other suitable copolymerizable monomers are acrylonitrile ', Acrolein and vinyl sulfofluoride. :

The hydrophilic monomer can be one of the following: acrylic acid, Methacrylic acid, erotonic acid, maleic acid, fumaric acid, itaconic acid, amides of acrylic and methacrylic acid, monoalkyl esters of maleic acid and vinyl pyrrolidine.

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The chlorine-containing copolymer becomes gelatin in latex form. This latex is obtained by emulsion polymerization of the various comonomers according to known emulsion polymerization techniques. The so-called primary dispersion, which is obtained directly after the emulsion polymerization, can be used as such or after adjusting its concentration. Widely varying concentrations can be used This will depend on the final concentration and viscosity required in the casting composition .

Suitable metal complexing agents. antistatic ^ agents are sulfosalicylic acid, 2,5-disulfohydroquinone, the sodium salt of ethylenediaminetetraacetic acid, Ethanolaminodiacetic acid, 'the sodium salt of N (o-hydroxyben "zyl1) - ^ aml'hodiacetic acid, the monosodium- ■ salt of vanadic acid, 3,5-egg sauce pyrocatechol, phosphonoacetic acid, Ethylene-1,2-diphosphonic acid, butylene-1,4-diphosphonic acid and ascorbic acid. ·

The known casting additives can be added to the coating composition of the substrate layer, such as dispersants, coating aids, antiseptics for the gelatin and thickeners, which are generally highly viscous, water-soluble Polymers are the only task of which is to adjust the viscosity of the casting composition to the desired level. An overview of the thickening of latices and the thickening agents, which can be used is by Houben-Weyl in "Methods of organic chemistry", Macromolecular substances, volume 14- / 1, pages 519 and 536, Georg Thieme-Verlag, Stuttgart (1961), been given.

The chlorine-containing copolymer is in the form of a primary Dispersion and added in the above-mentioned proportions to the aqueous gelatin solution, after which the plasticizer and possibly the antiseptic agent can be mixed with it in an aqueous solution. The viscosity of the casting composition thus formed is adjusted as desired and known casting additives become the composition given. Finally, the casting composition is

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tongue applied in a known manner to a polyester film, the J three to five times in only one direction, preferably lengthways, has been stretched. After drying the layer the polyester film is stretched three to five times in one direction, which is perpendicular to the first stretching direction, preferably in the transverse direction. .

The coating composition for the substrate layer is in one applied such a ratio that after the second stretching process a layer is obtained which has a thickness between 0.10 and 2 microns. ■ "■

According to the dimensional orientation of the Polyesterfllms by drawing in two mutually perpendicular directions of the polyester film carrying the substrate layer is passed through 'a heat-setting zone, where it is heated to a temperature between 180 and 220 ⁰ C, while the film in'beiden directions is kept under tension. This forms a dimensionally stable, completely clear polyester film. Hydrophilic layers, such as gelatin-containing silver halide emulsion layers, can be applied directly to the substrate layer and adhere firmly to it. of this layer "The adhesion of the hydrophilic layer to the polyester film is excellent both in the dry and in the wet state during the treatment of the photographic material in the various photographic processing baths". . ·

The examples given below are in particular on. the use of polyethylene terephthalate film as a support for the substrate layer. and the hydrophilic layer or layers · 'aligned. However, the substrate layer can also be used on other ^! 'Polyester films are applied, for example on polyesters obtained from the polycondensation of glycol or mixtures of glycols with terephthalic acid or mixtures of terephthalic acid with small amounts of other dicarboxylic acids, such as isophthalic acid, diphenic acid and sebacic acid.

The invention is illustrated by the following examples.

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Example 1 ".

There is a substantially amorphous Polyäthylenterphthalatfilm having a thickness formed approximately 2.2 mm in accordance with an impact extrusion process, starting from molten polyethylene terephthalate at a temperature of about 280 ⁰ C. The film is of on a cooling roll having a temperature of about 75 ° C quenched and then stretched in the longitudinal direction over a differential roller system at a temperature of 84 ⁰ C to 3.5 times the initial dimension.

On the film thus stretched, there is a layer in a ratio
brings:

ratio of 70 m / liter of the following composition

Latex. '335

1,1,1-tri (hydroxymethyl) propane 12 g

Thickener 14.25 ml.

'Sodium salt of sulfosalicylic acid 10g Gelatin 5g.

ULTEAVON ¥ (10%, aqueous. Solution) 5 ml Water, ■. . "'633 ml

The pH of the casting composition is adjusted to 8.2 with ammonia.

The latex used has a concentration of 20% by weight and is formed by the emulsion copolymerization of vinyl chloride, vinylidene chloride, n-butyl acrylate and itaconic acid (63 = 30: 5: 2 wt .- ^), as in the British patent 1 234 755 is described.

The thickener is a copolymer of ethyl acrylate and methacrylic acid (80:20% by weight ). It is added in the form of an aqueous dispersion at a concentration of 20% by weight. - "

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ULTRAVON ¥ is the trade name of Ciba AG, Switzerland, for a Dispersing agent made from the disodium salt of heptadecylbenzimidazole disulfonic acid "consists.

After the layer has dried, the film is increased by a factor of 3.5 "at a temperature of about 87 ° C in a tenter in Stretched transversely. The final thickness of the film is about 0.180mm.

The film is then fed into a hub of the clamping frame, where, -while it is held under tension, is heat-cured for one minute at about eirer temperature of 200 ⁰ C. After thermosetting, the coated film is cooled and rolled up in the normal manner.

The film thus thermoset is subjected to corona discharge and provided with a gelatin silver halide emulsion layer as used in X-ray photographic material will. The layers of the photographic material obtained in this way show very good adhesion to the polyester film support both wet and dry.

The adhesion in the dry state is before and after the handling ' is checked. For this purpose / the gelatin layer by means of a sharp knife scratched crosswise, after which a pressed on it Adhesive tape is torn off again immediately., The quality is only satisfactory if only very little Pieces of the photographic layer are torn off.

The adhesion when wet is tested by scratching the surface of the material and trying to use a Finger the gelatin layer after each photographic step Treatment (developing, rinsing, fixing, rinsing) rub off. The gelatin layer should be used during this rubbing not be damaged. . ',

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Example 2 ■ - _s

Example 1 is repeated with the difference that the elongated polyester film with the following casting

2 setting in a ratio of 70 m / liter "is coated:

t .

"- ~~ Latex 335 ml

3-hydroxymethyl-2,4-dihydroxypenta 5 ml

Gelatin - 10 g

■ ULTRAVON ¥ (see example 1) 5 ml

Water 640 ml

The latex also has a concentration of 20% by weight, however, this time it is obtained by emulsion polymerization of vinylidene chloride, methyl acrylate and itaconic acid (88: 10i2 Wt .- ^ Q.

Do transverse stretching and thermosetting as described in Example 1 , a gelatin silver halide emulsion layer, like them in photographic. X-ray material is used, attached to the substrate layer.

The layers adhere well to the film support both in the dry and in the wet state.

Example 3

Example 1 is repeated with the difference that the following coating composition is used for the substrate layer will:

Latex 350ml

Gelatin. 20 g

1,1, -1-tri (hydroxymethyl) propane 20 g . Water 610 ml

The latex used has a concentration of 20% by weight obtained by emulsion polymerization of vinyl chloride, • methyl acrylate and itaconic acid (88: 10: 2% by weight) ·

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Excellent adhesion of the gelatin silver halide emulsion layer is obtained both dry and wet

Example 4

Example 1 "is made with a substrate layer of the following Composition "repeats:.

Latex 350 ml

Gelatine "3Og"

4-hydroxy-2-hydroxymethylamyl alcohol 25 g

Water 595 ml

The latex is a copolymer made of vinylidene chloride, Vinyl chloride, methyl acrylate, and itaconic acid (58: 30: 10: 2 wt-ft).

A lithographic photographic emulsion exhibits excellent dry and wet adhesion. "■■ - ■ · .- ■

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Example 5

It is an amorphous polyethylene terephthalate film of 1.2 mm thickness prepared by the impact extrusion process by molten polyethylene terephthalate at a temperature of about 280 ⁰ C are on a Kühlzylirfder and then stretched to the 3j 5 times in the longitudinal direction.

The thus stretched film is exposed to a corona discharge and then ^{coated with the following solution in a ratio of 75 m 2} / liter:

Latex (as in Example 1) - 175 ml

Gelatin 20 g

1,2,4-trihydroxybutane. '35 g

Water 770 ml

An X-ray photographic emulsion layer is shown in FIG Excellent adhesion both dry and wet.

ν. ■ ■

Example 6

Example 5 is repeated with the difference that the following coating composition is used for ^e cue substrate layer; ■, ~ -

"Latex (as in Example 2). 125 ml Qilatine" 20 g

Sodium salt of sulfosalicylic acid 10g 1,1,1-tri (hydroxymethyl) propane 20g

Excellent adhesion of the hydrophilic layer is obtained in the dry and in the wet state,

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Example 7 '.

Example 1 is repeated with the difference that the elongated polyethylene terephthalate film is coated with the following coating composition in a ratio of 70 m / liter: ■ -. -

Latex (as in example 1) 335 ml

Gelatin 6g

Sodium salt of sulfosalicylic acid 10 g

o-sulfobenzoic acid. 10 g

Water '640 ml

Before application, the composition is brought to pH 8 by adding ammonium hydroxide « _f

After transverse stretching and heat setting, it becomes a gelatin-silver halide emulsion layer as used in X-ray photographic material is applied to the adhesive layer.

The layers show excellent adhesion both when dry and when wet. . _t

If in the above-described casting composition the o-sulfobenzoic acid is omitted, the substrate layer is completely obscured after stretching the carrier, which is the material for use as a carrier for. makes photographic materials completely unsuitable. . ■ ■

Examples 8 and 9

Example 7 is repeated. In the casting composition but o-sulfobenzoic acid by the same amount of itaconic acid or 2-sulfoethyl methacrylate replaces »In both cases you get a photographic X-ray material, its layers excellent adhesion both in dry and in, show when wet.

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Example 10.

Example 7 is repeated, but with the difference that the o-sulfobenzoic acid is replaced by 15 g of glutaric acid and the amount of water is 635 ml instead of 640 ml. Excellent adhesion of the layers in the dry and in the wet state is obtained. . ^;

Example 11

Example 7 is repeated except that the elongated polyethylene terephthalate film has the following

Casting composition in a ratio of 70 m / liter

is coated:>

Latex (as in Example 1) 420 ml

Gelatin 30 g

Sodium salt of sulfosalicylic acid 12 g Adipic acid (as a 20% aqueous solution) 120 g ULTRAVON ¥ (10% aqueous solution) 6 ml ■ ^ Water '574 ml

An X-ray photographic material and its layers are obtained show excellent adhesion both dry and wet.

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Claims (1)

Claims Process for improving the adhesion of hydrophilic layers to a dimensionally stable polyester film carrier, characterized in that the "process comprises the following steps: longitudinal stretching of the polyester film carrier, then application of a single substrate layer, stretching of the coated polyester film carrier in the transverse direction and heat curing to 180-22 ° C ■ , the substrate layer being 30 to 80% by weight of a chlorine-containing copolymer, 5 to 30% by weight of gelatine, 5 to 40% by weight of plasticizer for the gelatine, and 0 to 30% by weight of a metal complex-forming antistatic agent contain 2 _{o The} method according to claim 1, characterized in that a polyester film made of polyethylene terephthalate is used, 3c method according to each of the claims. 1 and 2, j characterized in that a chlorine-containing copolymer comprising 70 to 95 parts by Ji vinyl chloride and / or vinylidene chloride ₉ Oj5Ois 10 Ge ¹ Wο7% of a hydrophilic monomer and O ₅ 5 to 25 .GreWo-% of at least one other copolymerisable Contains monomers, is used = 4, method according to any one of claims I ₅ 2 and «3 ₅ characterized gekennzeichnets that as chlorine-containing copolymer is a copolymer of vinylidene chloride, vinyl chloride, _s n-butyl acrylate and itaconic acid ~ (63 wt 30s5s2 _s -?%) Used wircL 5 ° method according to each of claims I ₉ 2 and 3 _? characterized ₉ that a mixed polymer of vinylidene chloride, methyl methacrylate and itaconic acid (88s 10s2 wt. ₀ %) is used as the chlorine-containing copolymer. .m · A-G 1133 - 15 - 6. The method according to any one of claims 1 to 5, characterized in that the chlorine-containing copolymer is added to the casting "composition of the substrate layer in the form of a primary dispersion in water, which is obtained directly by emulsion copolymerization of the various monomers." 7. The method according to any one of claims 1 to 6, characterized in that that the sodium salt of sulfosalicylic acid is used as a metal complex-forming antistatic agent. 8. The method according to any one of claims 1 to 7, characterized in that the plasticizer Ij 1, 1-tri (hydroxymethyl) propane is used. 9. The method according to any one of claims 1 to 7, characterized in that that o-sulfobenzoic acid, itaconic acid, 2-sulfoethyl methacrylate, glutaric acid or adipic acid is used, ' - 10o method according to any one of claims 1 to 9 »thereby characterized in that the hydrophilic layer, which is applied to the substrate layer, consists of a photosensitive Gelatin-silver halide emulsion layer. 11. Silver halide photographic light-sensitive material, characterized in that it is produced according to the process of claim 10 is obtained. A-G 1133 · -. 16 - 309849/1 1 19