DE2510734B2 - Process for coating glass bottles with a transparent protective layer - Google Patents

Description

R-C-

R. C-R

R'-N N

R "

used, wherein R is hydrogen, an alkyl or aryl radical, R 'a cycloalkyl, helerocycloalkyl or R radical, R ″ an optionally alkyl or aryl-substituted alkylene or arylene radical and X Hydrogen or one

The coating of glass bottles with a firmly adhering, uniform and transparent plastic layer gives these bottles when used for carbonated drinks, such as mineral water, beer, Fruit juice drinks and the like, an extraordinary security and extends the returnable bottle Useful life. As a result of impact and impact, but also by heating in sunlight or on It is heat sources in the past

ίο there have been frequent explosions of unprotected bottles, causing various serious physical injuries, in particular eye injuries, to people.

Some of the previously known coatings for

this purpose have the disadvantage that the top layer becomes cloudy with repeated cleaning, which, when using thermoplastic materials, is possibly due to a naci.icrystallization effect of the plastic. ge bottles give a negative visual impression and are therefore undesirable in terms of sales psychology.

It has now been found that glass bottles can also be used without these and other disadvantages while at the same time being good can coat handling properties if one considers the process for coating glass bottles with a transparent, thermosetting protective layer so that one starts with the pure glass noses an aqueous or alcoholic silane size

treated in, the bottles are optionally dried and then ^{heated to a temperature of 180 to 250 0} C, the powder coating electrostatically from! ^ - Epoxy compounds with at least one epoxy group in the molecule and a lower melting point of

Ii> 40 ° C and hardeners and processing additives applies, with amidines of the general formula as hardeners

R — C — N

C remainder

R-C-N

I I

R R '

means, and optionally with further supply of heat the powder layer hardens.

2. The method according to claim _1, characterized in that the coated glass bottle is subjected to curing at a temperature in the range from 140 to 240 "C. Preferably 180 to 200 ° C.

3. The method according to claims 1 and 2, characterized in that one as eyclisches Amidine 2-phenyl-imidazoline is used.

4. The method according to claims I to 3, characterized characterized in that the cyclic amidines in amounts of 4 to 12 wt .-%. preferably 6 to 8 Wt%. based on the total amount of powder coating.

5. The method according to claims 1 to 4 thereby gekennzeichnei. that the powder coating in the ! ^ - Adds soluble dyes to epoxy compounds.

b. Process according to Claims 1 to 3, characterized in that the glass bottles are coated with the powder paint by whirl sintering or electrostatic whirl sintering.

R-C-

R'-N

-C-R

C. R "

used, in which R is hydrogen, alkyl or aryl radical, R 'is a cycloalkyl, hydroalkyl or R -kcst. R "is an optionally alkyl or aryl-substituted alkylene or arylene radical and X is hydrogen or a

R-C N

C remainder

R -C-R

N R '

means, and with the addition of additional heat, if necessary, the powder layer hardens.

The protective layer applied in this way is highly elastic and has excellent adhesion, so that the Glass breakage or bursting of the bottle, the glass splinters cannot penetrate to the outside. After the destruction the glass bottle retains its shape in full. The kinetic energy that occurs is due to stretching and heating the plastic coating implemented.

The resistance of the coating to hot, alkaline rinsing solutions is of particular advantage. in which the bottles are cleaned before the luxury food is filled. This is particularly true Dimensions for returnable bottles, which are subjected to intensive cleaning before each filling process will.

The advantage of the coating according to the invention is that even after repeated rinsing in the hot, alkaline washing lye, no softening of the material and no loss of adhesion occurs. Even visually show sict. no changes.

The glass bottles coated in this way can be used as Containers for carbonated drinks can be used safely if they break or burst.

When used as returnable bottles, the useful life of a coated bottle is essential longer than that of the unprotected bottle, which as a result of the Movements caused by rubbing sharp edges against each other and rinsing processes in hot alkaline solutions The surface is heavily used or easily damaged.

To carry out this process, the cleaned glass bottle is first used with an aqueous one or alcoholic Silanschlichie treated. For the Treatment uses silanes with radicals :, which can be assigned to two different function types.

First of all, these are lower alkoxyresies. in particular methoxy and Älhoxyreste, which react with OH groups on the glass surface, and secondly organic residues with such functional groups that can react either with the I ^ epoxy compounds, such as amino groups, or with the hardener, z. B. epoxy groups, glycidyl radicals and the like γ-aminopropyl-trimethoxysilane, γ-aminopropyl-triethoxy-silane, glycidyloxypropyl-trimethoxy-silane, glycidyloxypropyl-triethoxy-silane, etc. Mixtures with similar functional radicals can also be used, ie mixtures groups reactive with epoxy groups or groups reactive with the hardeners. The treatment of the glass bottle can take place, for example, by dipping or spraying with the sizing agent. The bottles treated in this way can then be dried separately. The drying can be done simultaneously to 250 ⁰ C by heating the bottle at 180, ie to a temperature as occurs in the Flaschcnhcrstellung during the Abkühlprozesscs.

The application of the powder varnishes described below to the heated glass bottles is done according to known methods, e.g. B. by electrostatic powder spraying; but it can also be caused by vortex sintering or electrostatic vortex sintering etc. take place.

The immediate melting of the powder, which is in the melting range of approx. 100 ^° C., results in the excellent, transparent flow of the film.

The supply of heat can - if the existing heat capacity is not sufficient for curing - be continued even after the application of the permanent varnish until the crosslinking is complete.

The glass nose coated in this way is subjected to curing at a temperature in the range from 140 to 240.degree. C., preferably 180 to 200.degree.
For the production of the finely divided mixtures, which are to be used as powder coatings, are suitable! ^ - Epoxy compounds with at least one 1,2 Fnoxidgruppe in the molecule and a lower melting point of> 40 "G 40 "C and below are solid, including higher molecular weight compounds (so-called solid resins), and those that are due to their symmetrical structure or the size of the 1,2-epoxy group

is bonded carbon residues are solid, and on the other hand, those created by the reaction of liquid 1,2-epoxy compounds with more than one epoxy group have been prepared per molecule with primary or secondary amines in such an amount that the Adduct still contains at least one 1,2-epoxy group per molecule on average (so-called adduct hardeners).

The 1,2-epoxy compounds can be saturated as well as unsaturated and aliphatic, cycloaliphatic, aromatic or heterocyclic. You can furthermore contain those substituents which are not disruptive under the mixing or reaction conditions Cause side reactions. No side reactions cause, for example, alkyl or aryl substituents

jci ten, hydroxyl groups. Ether groups and the like emerged. Suitable compounds belong to the following classes of substances: Single or multiple epoxides unsaturated hydrocarbons, halogen-containing epoxides, epoxy ethers of single or multiple alcohols and Phenols, epoxy esters of monobasic or polybasic acids and N-containing epoxides.

Of the solid resins, 1,2-epoxy compounds are used for this purpose more than one epoxy group in the molecule is preferred, c-'r ^ n epoxy equivalent weight lies between 500 and 1000. These are, for example, the solid, polymeric polyglycidyl polyethers des ^, 2-bis- (4-hydroxyphenyl) -propane, which, for example, by reaction of 2,2-bis- (4-hydroxyphenyl) -propane with epichlorohydrin in molar ratios of

4 ", I: 1.9 to 1.2 (in the presence of an alkali hydroxide in the aqueous medium) can be obtained. Polymeric polyepoxides of this type can also be obtained by Implementation of a polyglycidyl ether of 2,2-bis (4-hydroxyphenyl) propane with less than the equimolecular

V) laren amount of dihydric phenol, preferably in Presence of a catalyst such as a tertiary amine, a tertiary phosphine or a quaternary Phosphonium salt. The polyepoxide can also be a solid epoxidized polyester, for example

V ") is obtained by converting a polyvalent one Alcohol and / or a polybasic carboxylic acid or its anhydride with a low molecular weight Polyepoxide. Examples of such low molecular weight polyepoxides are the liquid diglyci-

bo dylether of 2,2-bis- (4-hydroxyphenyl) -propane, diglycidylphthaial, Diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl adipate, diglycidyl maleate and the 3,4-epoxycyclohexylmethyl ester of 3,4-epoxycyclohexane carboxylic acid.

h> Mixtures of solid polyepoxides can also be used. /. B. a mixture of a polyepoxide, the melting point of which is between 120 and IbO ⁰ C, and a polyepoxide with a melting point

point between 60 and 80 "C {melting point determined by Durr's mercury method a η s). Suitable mixtures contain between 30 and 50% by weight of a solid polyglycidyl ether of 2 ^ -Bis- (4-hydroxyphenyl} propane with an epoxy equivalent weight between 1650 and 2050 and one Melting point from 120 to 160 ° C and between 50 and 70 wt .-% of a solid Polyglycidylpoiyäthers des 2 ^ -Bis- {4-h> droxyphenyl) propane with an epoxy equivalent weight between 450 and 525 and a ι ο Melting point from 60 to 80 "C

If a high level of epoxy functionality appears to be desirable, a preferred polyepoxide is the polyglycidic ethers of 1,1 2-tetra- (4-hydroxyphenyl) ethane.

Epoxidized polybutadienes can also be used for this purpose.

As mentioned earlier, in addition to the so-called solid resins, adduct hardeners are also suitable for carrying out the process according to the invention. Such solid adduct hardeners can, for example, from liquid polyepoxides of polyunsaturated hydrocarbons, such as vinylcyclohexene, dicycloblockadiene and the like, Epoxy ethers of polyhydric alcohols and phenols etc. and aliphatic, cycloaliphatic and aromatic Diamines are made. A prerequisite for the suitability of such an adduct is that the lower melting point is above 40 ° C.

Just like the pure epoxy compounds, their mixtures, for example those of mono- and polyepoxides, can be used by the process according to the invention.

Suitable cyclic amidines, i. H. Imidazoline derivatives for the purposes of the present invention are

2-methylimidazoline, 2,4-dimethylimidazoline,

2-ethylimidazoline, 2-ethyl-4-methylimidazoline,

2-benzylimidazoline, 2-phenylimidazoline.

2-phenyl-4-methylimidazoline,

2- (o-tolyl) -imidazoline, 2- (p-tolyl) -imidazoline,

1,4-tetramethylene-bis-imidazoline,

!,!, S-trimethyl-M-tetramethylene-bis-imidazoline, l ^ -trimethyl-M-tetramethylene-bis-imidazoIin,

1.l ^ -trimethyl-l ^ -tetramethylene-bis ^ -methylimi dazolin,

³⁵

dazolin, 2- (m-pyridyl) -imidazoline,

2- (p-pyridyl) -imidazoiin,

1,2-phenylene-bis-imidazoline,

1,3-phenylene-bis-imidazoline,

1,4-phenylene-bis-imidazoline,

1,4-phenylene-bis-4-methylimidazoline and others. m.

⁴⁵

50

Mixtures of these imidazoline derivatives can also be used are used according to the invention. 2-Phenyl-imidazoline is formed from these groups of imidazolines preferred. These compounds can act as sole hardeners or crosslinkers for the 1,2-epoxy compounds can be used.

The imidazoline derivatives described above eo are used in such amounts that 4 to 12 wt .-%, preferably 6 to 8 wt .-%, based on the Total amount of powder paint, come.

To improve the leveling properties of the coatings, so-called Leveling agent added. These agents can be chemical compounds or mixtures thereof act of different chemical types, e.g. B.

polymeric or monomeric compounds, acetals, wis polyvinyl formal, polyvinyl acetate Polyvinyl butyral, polyvin) lacetobutyral or Di-2-ethyhexyl-i-butyraldehyde-acetal, Di-2-ethylhexyl-n-butyraldehyde acetal, Diethyl-2-ethylhexanaI-acetal, Di-n-butyl-2-ethyI-hexanal-acetal, Di-i-butyl-2-ethylhexanaI-acetal, Di-2-ethyl-hexyl-acetaldehyde-acetal u. Ä ^,

Ether, such as the polymeric polyethylene and polypropylene glycols, copolymers of n-butyl acrylate and Vinyl isobutyl ether, ketone-aldehyde condensation resins, solid silicone resins or mixtures of Zinc soaps, fatty acids and aromatic carboxylic acids, and the like are also commercially available for this purpose Products such as Modaflow® are offered whose chemical character is unknown to consumers and from who only knows that it is a complex, polymeric, effective liquid key, such leveling agents can be used in the approaches,! in quantities of 0.2 to 5.0% by weight, based on the total amount of powder, may be included.

The other common components of the powder coating mixture, as in the 1,2-epoxy compounds soluble dyes, stabilizers and others can be obtained to the amount 1, L'-epoxy compound and hardener, vary within a wider range. she can are based on the requirements for the quality of the coatings.

Before they are used, the powder coating components are intimately mixed at temperatures below Curing temperatures, extruded and then ground. For practical use, a particle size of <100μ aimed at, with the maximum particle size between 30 and 50 μ should be.

The layer thicknesses of the cured coatings can vary depending on the use of the bottles 50 and 250 μπι be set.

Unrefined and pure glass bottles were initially mixed with aqueous or alcoholic γ-aminopropyl-triethoxysilane solution (1.5% by weight) at room temperature coated with an approximately monomolecular layer and then dried.

The 1,2-epoxy compounds used with the special characteristics, in practice mostly as Designated epoxy resin, with the imidazoline derivatives acting both as crosslinkers and hardeners and the leveling agent in the specified Mixed weight ratios, extruded and then ground. The particle size of the powder ingredients was <100 µm. The frequency distribution of the particle size was in the range from 30 to 50 μm Maximum. These fine-grained mixtures were then applied to the preheated glass bottles by electrostatic powder spraying and subsequently if necessary, at the stated temperatures and times. The properties of the obtained Coatings were subjected to the following tests.

example 1

2-Phenyl-imida2.olin was processed with the specified epoxy resin and a small amount of leveling agent in the following ratio to the coating powder:

Solid epoxy resin, on the base
of an adduct of 2,2-bis (4-hydroxyphenyl) propane (diane) and
Epichlorohydrin, which one
HCI cleavage subject and
then with another dian
was implemented, and which one after
According to the manufacturer, an epoxy equivalent weight of 900 to 1000
possesses what an epoxy value of
0.10 to 0.11, and one
Sdimclzbereich from 40 to 100 C
2-phenyl-imidazoline
Leveling agents, which * in the I landel
line of the name Modaflow '
available isi

93.5% by weight 6.0% by weight

This r-'ormulicrung was applied hot at 200 ^'1 C "glass bottles and cured for 5 minutes at IKO (mti the coated Raschen were wirgenommen following tests.:

a. Visual assessment:

The surface showed a bare, smooth appearance.

b. .Layer thickness:
60 to 70 µm

c. Burst pressure:

The flaps burst at an internal pressure of 22 to 2b atii with a fine splinter image.
The plastic jacket held the resulting splinters together completely.

d. Test in the washing machine:

The test wash liquor consisted of a mixture of a bottle detergent based on the Nairium salt of a polyphosphate with a Sodium hydroxide solution (0.25 / 2.5% by weight) and apply to the bottles at 85 "C for 5 minutes allowed to act. The total time of the cycle in the washing machine was 30 minutes. Of the After that, plastic showed no negative changes.

e. Test in the line simulator
Bottle tempera door 80 "C:

The bottles were first filled with 80 C hot water and then placed in a water bath with a temperature of 80 C for 10 minutes. The heated bottles were then tested in the line simulator for 1 minute.
After the test, no abrasion points were found on the plastic coating in the area of the bottle body.
χ 1 minute runtime in
Line Simulator:

The test explained above was repeated five times.
No damage was found.

f. impact test
(Splinter cohesion):

The impact test was carried out with a layer energy of 73 kg / ct.i. A steel ball with a diameter of 80 mm fell from a height of 350 mm onto the empty bottle lying horizontally ^{at a guide angle of 120 ° C.}
The swift broke up and were deforniieri from the blow. However, they were preserved as a whole without splinters of glass escaping to the outside.

In order to assess the coating agent in the event of stoli stress, the "puncture test with electronic data acquisition" was carried out in accordance with DIN 53 373. Based on his results, he showed the flexibility and resistance of a plastic film.
The layer thicknesses of the films were between 115 and 138 μm. The following test settings were used:

Sample shape Flat film machine Dvnatester Test temperature 24 ( Relative humidity 70'V ₁ , Transverse body cr Hemisphere gcbnivsc from 10 exams Damage force l \ 14.17 kp Damage work VK 2.67 kncm Piercing work \\\. _c . 4.05 k pcm Damage deformation /., 5.08 mm

Example 2

2-Phenvl-imidazoiin was given with the Epoxy resin as well as a small addition of leveling agent in the following ratio to the Heschichuingspulver processed:

Solid epoxy resin (according to Example 1) 93.5% by weight
2-phenyl-imidazoline 6.0% by weight

Leveling agent (according to Example I) 0.5% by weight

[This formulation was applied to glass bottles, which had a temperature of approx. 240T at the moment of application. It happened! .One Post-curing.

The tests of the coated bottles were carried out as explained in Example 1, with the Results from Example 1 were obtained.

Example 3

1.4-Tetramethylene-bis-imidazoline was with the specified epoxy resin and a small addition of leveling agent in the following ratio to the Coating powder processed:

Solid epoxy resin (such as

under example 1) 94.0% by weight

1.4-tetra-methylene-bis-imidazoline 5.5% by weight

Leveling agent (according to Example 1) 0.5% by weight

This formulation was applied to glass bottles which had been heated to 200 ° C. It would no post-curing carried out. The following tests were then carried out:

a. Visual assessment:

The surface showed a bare, smooth appearance.

b. Layer thickness:
70 to 80 μm

c. Burst pressure:

The bottles burst at an internal pressure of 20 to 24 atmospheres with a fine splinter image. Of the Plastic coating held the splinters together.

d. Test in the washing machine:

The test was carried out according to Example Id.

After the specified time, there were no negative changes in the plastic here either.

e. Test in the line simulator
Tests according to example Ie:

The plastic coating showed only minor abrasion points. After 5 χ Ι minutes of running time were further damage not found.

f. impact test (splinter cohesion)
Bearing according to example I:

The bottles broke and were deformed by the blow, but remained as a whole obtain.

U e i s ρ i e I 4

2-Phenyl-4-methyl-imidazoline was given with the Epoxy resin and a small amount of flow control agent in the following ratio / u to the coating powder processed:

solid epoxy resin (according to example I)
-> nu 1 λ ^ .u..ι; _m ;, j .., _Λ ι; ~

Leveling agent (according to example I)

94.5% by weight / n
^ no: «... au

0.5 wt%

This formulation was applied to hot glass bottles at 200 ° C. These coatings were then cured for 10 minutes at 200 ° C. and subjected to the following tests:

a. Visual assessment:

The surface showed a bare, smooth appearance.

b. .Layer thickness:
60 to 80 μm

c. Burst pressure:

The bottles burst at an internal pressure of 20 to 24 atmospheres with a fine splinter image. Of the Plastic coating did not let any splinters penetrate to the outside.

d. Test in the washing machine:

Test according to example Id. No negative changes after the test period,

e. Test in the line simulator
Tests according to example Ie:

Except for a few slight rub-offs, the coating was completely preserved.
After a running time of 5 χ 1 minute, there were no further injuries to the plastic layer.

f. impact test (split cohesion)
Test according to example I f:

The bottles broke and were deformed by the blow, but remained as a whole obtain.

Example 5
(Comparative tests according to the state of the art)

Solid epoxy resin (according to Example 1) '95.3% by weight
Dicyandiamide 4.2% by weight

Leveling agent (according to Example 1) 0.5% by weight

The application was carried out according to the example

The bottles so coated were with the coated bottles of Example I on their Alkali resistance compared.

The liquor I described in Example 1 was used. The lye II, however, was more alkaline than lye I and consisted of the above mixture of bottle cleaning agent with sodium hydroxide solution (0.25 / 4% by weight). The alkali resistance was determined at 85 ° C. The lye was effective in each test Minutes on the coated bottles. After the film had been evaluated, the bottles were again immersed in the detergent solution for another 5 minutes.

The following results were obtained:

Lye I

l. effect - '"duration

According to example I.

uncon- cerned

damaged film film

5 minutes 10 minutes 15 minutes 20 minutes 25 minutes 30 minutes 35 minutes 40 minutes 45 minutes 50 minutes

Lye Il

0 0 0 0 0 0 A

Exposure time

Corresponds to Example I.

ominous- iingc-

schiidig- ril / i: r ler movie movie

5 minutes 10 minutes 15 minutes 20 minutes 25 minutes

0 0 0 0 Λ

0 0 A

State of the art

undamaged film

scratched film

0 0 0 T T T A

0 0 0 T A

State of the art

undamaged film

scratched film

0 0 A

0 A

Explanation of symbols: 0 = no change.

T = beginning of the clouding of the coating material. A = beginning of the detachment of the coating material.

Claims (1)

Patent claims: I. Process for coating glass bottles with a transparent, thermosetting protective layer by applying powder coatings 1 ^ epoxy compounds with at least one 1,2-epoxy group in the molecule and a lower one Melting point of> 40 ° C and hardeners as well as processing additives on the silaoized glass surface and hardening of the powder layer at increased Temperatures, characterized in that the surface of the pure Treated glass bottles with an aqueous or alcoholic silane size, which Raschen optionally dries and then to a temperature heated from 180 to 250 "C, electrostatically the Powder coating is applied, using amidines of the general formula as hardeners