DE2201462C2 - Process for heating thermoplastic polymers to thermally deform them - Google Patents

Description

R-CN
or polymers with repeating units

DE
ί i

-c — ο-Ι I

G CN

20th

25th

worm

D, E and G alkyl, aryl or cycloalkyl groups, heterocyclic groups, nitrile groups or Water '"> for? And

R is an alkyl, aryl, cycloalkyl or alkenyl group with 2-10 carbon atoms, a heterocyclic group or hydrogen

35 mean used.

3. The method according to claim 1 or 2, characterized in that one for dielectric heating of thermoplastic films with a thickness of more than 0.13 cm and a dielectric Loss factor of more than 0.003 and less than 0.01 the thermoplastic film with the carrier release film arranged in pairs in a stack and heated by means of radio frequency energy, with each unheated thermoplastic film at one end of the stack during a process cycle Material fed together with the carrier release film and from the other end of the Stack of heated film of thermoplastic material with carrier release film is removed.

The invention relates to a method for dielectric vision Heating of thermoplastic materials using electromagnetic field energy for thermal Deformation.

_{So far, infrared units} have been used for the thermal deformation of plastic materials of low thickness in order to soften the materials before deformation. In order to achieve reasonable heating rates and uniform heating, hot air ovens, heating from two sides and other modifications of heating techniques have been used. Since plastic substances are generally materials with a relatively low thermal conductivity, such heating is limited to thin products for economic reasons Energy is lost.

Thick thermoplastic sections generally cannot be uniformly and completely within Warm up a short line with infrared heat or hot air systems. Though energy from radio frequencies capable of heating certain materials quickly, completely and evenly, most can be usual thermoplastic materials by radio frequency energy not to a temperature for the heat thermal deformation.

The radio frequency heating unresponsiveness of most thermoplastic polymers is due to the generally due to their non-polar character. Non-polar materials speak of dielectric heating not on and various thermoplastic polymeric materials containing polar groups speak up dielectric heating is not essential because the polar groups often either arranged symmetrically, due to the electron forces of other groups bound or have become immobile due to networking effects.

Thermoplastic polymers that are usually sensitive to heating by electromagnetic field energy do not respond, usually have a very low dielectric loss factor of less than 0.01.

It has been found that thermoplastic polymers which have a dielectric loss factor of less than 0.01, regardless of whether they are in the form of thick or thin films, quickly and can be heated evenly by means of electromagnetic field energy if you use the thermoplastic Polymers mixed with 1 -20% by weight of a material which has a polar region and at least one Has nitrile group

By mixing the material with a polar region, the thermoplastic polymers, which usually do not respond to heating from electromagnetic field energy, this one Very sensitive to energy and can be completely heated quickly and evenly without a significant change in their physical properties occurs. Thick sections that haven't been could easily be heated to thermoforming temperatures without either degradation of the Polymers themselves or other significant changes in their physical properties have taken place, can according to the invention quickly and evenly without influencing the physical properties be heated.

The invention relates to a method for heating thermoplastic polymers with a dielectric Loss factor of less than 0.01 using electromagnetic field energy for the thermal Deform, which is characterized by. that the thermoplastic polymer with 1 -20% by weight of one Material with a polar region mixed with at least one nitrile group and the mixture obtained heated by radio frequency energy.

The material having the polar region can be a simple organic compound having a nitrile group or a polymeric material having a nitrile group. The admixture of the material with the polar area can be used before, during and after the polymerization of the

thermoplastic polymers.

After mixing the materials with the polar region with the thermoplastic polymer, the Mixture treated with radio frequency energy, which causes the material to be heated quickly. The material can be heated to any desired temperature by increasing or decreasing the treatment time but most applications require the material to be heated to its softening temperature, d. H. the temperature at which the material deforms when pressure is applied (0.39 kg / cm or more).

The most commonly used radio frequency energy has frequencies between 1 MHz and 2750 MHz (Mega Hertz), preferably between 1 MHz and 140 MHz, in particular between about! MHz and 100 MHz is. In general, higher frequencies effect faster heating. As Materi J with a polar area, compounds of general formula

R-CN

or polymers with repeating units
/ DE

i) cyanoalkyl, e.g. B, cyanopropyl, cyanobutyl,

Cyanoethyi etc,
j) haloalkyl, e.g. chloromethyl, bromopemyl,

Chlorooctyl, etc.,
k) alkyl substituted with an acyl group of

general formula

10

15th

-c — ο-Ι I

G CN

25th

worm

35

D, E and G alkyl, aryl or cycloalkyl groups, heterocyclic groups, nitrile groups or hydrogen and

R is an alkyl, aryl, cycloalkyl or an alkenyl group with 2 - 10 carbon atoms, a heterocyclic group Group or hydrogen are used.

Preferred simple compounds are those of the general formula

R-CN

in the R

(1) an alkyl radical having 1 to 18 carbon atoms, e.g. B. Methyl, ethyl, propyl, butyte, isobutyl, octyl, Dodecyl, etc. including substituted alkyl having 1 to 18 carbon atoms, such as

a) alkoxyalkyl, e.g. B. Äthoxypropyl, Methoxybutyl, Propoxymeiiiyl etc.,

b) aryloxyalkyl, e.g. B. phenoxyethyl, naphthoxymethyl, Phenoxypentyl etc.,

c) aminoalkyl, ζ. B. aminobutyl, ammoatnyi, Aminopropyl etc.,

d) hydroxyalkyl, ζ. B. hydroxypropyl. Hydroxyoctyl, Hydroxymethyl etc.,

e) aralkyl, e.g. B. benzyl, phenethyl, etc.,

f) alkylaminoalkyl, e.g. B. methylaminopropyl, methylaminoethyl etc. and also dialkylaminoalkyl, z. B. Diethylaminoethyl, Diffiethylaminopropyl, Propylaminooctyl etc.,

g) arylaminoalkyl, e.g. phenylaminoalkyl, di- (3) phenyläfninoalkyl, N-phenyl-N-ethylaminopentyl, N-Phertyl-N-ethylaminohexyl, Naplv ethylaminuäthyl etc.,

h) nitroalkyl, 2. B. nitrobutyl, nitroethyl, nitropentyl etc.,

- C —R

in which R is hydroxy, hydrogen; Aryl, ζ. Β. Phenyl, naphthyl, etc., substituted alkyl, lower alkyl of 1-8 carbon atoms, ζ. B. methyl, ethyl, propyl, etc., substituted and unsubstituted amino, ζ. B. Di-lower-alkyl-amino, lower alkoxy with 1-8 carbon atoms, ζ. Β. Butoxy, methoxy etc. is aryloxy, or

(2) an aryl radical, e.g. B. phenyl, naphthyl, anthryl, fluorenyl, etc. including substituted aryl groups. how

a) alkoxyaryl, e.g. B. ethoxyphenyr, methoxyphenol, Propoxynaphthyl etc,

b) aryloxyaryl, e.g. B. phenoxyphenyl, naphoxyphenyl, Phenoxynaphthyl etc,

c) aminoaryl, e.g. B. aminophenyl, aminonaphthyl, Aminoanthryl etc,

d) hydroxyaryl, e.g. B. hydroxyphenyl, hydroxynaphthyl, Hydroxyanthryl etc,

e) biphenylyl,

f) alkylaminoaryl, e.g. B. methylaminophenyl, methylaminonaphtyl, etc., including Dialkylaminoaryl, ζ. B. Diethylaminophenyl, Dipropylaminophenyl etc,

g) arylaminoaryl, e.g. B. phenylaminophenyl, diphenylaminophenyl, N-phenyl-N-ethylaminophenyl, N-phenyl-N-chloraminophenyl, naphthylaminophenyl etc,

h) nitroaryl, e.g. B. nitrophenyl, nitronaphthyl,

Nitroanthryl etc,
i) cyanoaryl, e.g. B. cyanoptienyl, cyanonaphthyl,

Cyanoanthryl etc,
j) haloaryl, e.g. B. chrophenyl, bromophenyl,

Chloronaphthyl etc,
k) aryl substituted with an acyl group of

general formula

30th

45

- C —R

in which R is hydroxy, hydrogen, aryl, e.g. 3. Phenyl, naphthyl, etc. Amino, including substituted ones, e.g. B. di-lower-alkylamino, lower alkoxy with 1-8 carbon atoms, e.g. butoxy. Methoxy, etc. aryloxy, e.g. B. phenoxy. Naphthoxy, etc., lower alkyl of 1-8 carbon atoms, e.g. B. methyl, ethyl, propyl, buty 'jsw. is,
1) alkaryl, e.g. B. ToIyI, ethylphenyl, propylnaph-

thyl etc, or

a cycloalkyl radical with 4-8 carbon atoms in the cyclic nucleus, e.g. B. cyclobutyl, cyclohexyl, Cyclopentyl, etc. including substituted cycloalkyl, A'ie

a) alkoxycycloalkyl, e.g. B. ethoxycyclohexyl, methoxycyclobutyl, propoxycyclohexyl etc.,

22 Ol

Phenoxycyclohexyl, phenoxycyclopentyl

b) aryloxycycloalkyl, e.g. B.
Naphthoxycyclohexyl,
etc.,

c) aminocycloalkyl, e.g. B. Aminocyclobutyl, Ami ' nocyclohexyl, aminocyclopentyl etc,

d) hydroxycycloalkyl, e.g. B. Hydroxycyclohexyl, Hydroxycyclopentyl, hydroxycyclobutyl, etc.,

e) arylcycloalkyl, e.g. B. phenylcyclohexyl, phenylcyclobutyl etc.,

f) alkylaminocycloalkyl, e.g. B. methylaminocyclohexyl, Methylaminocyclopentyl etc. and also dialkylaminocycloalkyl, ζ. B. Diethylaminocyclohexyl, Dimethylaminocyclobutyl, dipropylaminocyclooctyl etc,

g) arylaminocycloalkyl, e.g. B. phenylaminocyclohexyl, diphenylaminocyclohexyl, N-phenyl-N-ethylaminocyclopentyl, N-phenyl-N-methylaminocyclohexyl, naphthylaminocyclopentyl (1), etc.,

h) nitrocycloalkyl, e.g. B. NitrocyclobutyL, Nitrocy-

clohexyl, nitrocyclopentyl etc,
i) Cyanocycloalkyl. z. B. Cyanocyclohexyl, Cya-

nocyclobutyl, cyanocyclopentyl etc.,
j) halocycloalkyl, e.g. B. chlorocyclohexyl, bromocyclopentyl, chlorocyclooctyl etc,

k) Cycloalkyl substituted with an acyl group of the general formula

Il

- C —R

in which R is hydroxy, hydrogen, aryl, ζ. Β. Phenyl, naphthyl, etc. amino and substituted Amino, ζ. B. Di-lower alkylamino, lower alkoxy with 1-8 carbon atoms, ζ. Butoxy, methoxy, etc. aryloxy, e.g. B. Phenoxy, naphthoxy etc., lower alkyl with 1-8 carbon atoms, e.g. methyl, ethyl, Propyl, butyl etc,

(4) a heterocyclic and substituted heterocyclic group with 5-6 members in the hetero nucleus with is at least one sulfur, selenium, nitrogen or nitrogen atom, such as a thienyl group,

z. B. a benzothienyl group, a pyrrolyl group, z. B. a nitropyrrolyl group, a pyrrolidinyl group, z. B. a pyrrolyl group, a pyrrollinyl group, a benzopyrrolyl group, e.g. Legs Indoiyl group, a carbazolyl group, a furyl group, z. B. a furfuryl group, a benzofuryl group, etc., a pyridyl group, e.g. Legs Halopyridyl group, an aminopyridyl group, a hydroxypyridyl group, an alkylpyridyl group, a nitropyridyl group etc, a piperidyl group, a quinolyl group, an acridinyl group, a pyrranyl group, a benzopyranyl group, a pyrazolyl group, an oxazolyl group, a Thiazolyl group etc, or (2)

(5) hydrogen or

(6) an alkenyl group having 2-10 carbon atoms, e.g. vinyl propenyl, butenyl pentenyl etc., including substituted alkenyl group

(a) alkoxyalkenyl

(b) aryloxyalkenyl

(c) Aminoaikenyi

(d) hydroxyalkenyl

(e) aralkenyl, e.g. styryl,

(f) alkylaminoalkenyl

(g) arylamirtolealkenyl

(h) nitroalkenyl

(i) cyainolalkenyl or

(j) haloalkenyl

Preferred polymeric materials with groups with polar areas are characterized by the following structure:

Ü E

.G CNj
D, E and G have the following meanings:

an alkyl group of 1-18 carbon atoms, e.g. B. fvieihyi, Aihyi, PrGpyl, Butyl,! Sobüty !, Octy ', Dodecyl, etc. including substituted alkyl group having 1 -18 carbon atoms such as

a) alkoxyalkyl, e.g. B. ethoxypropyl, methoxybutyl, Propoxymethyl etc.,

b) aryloxyalkyl, e.g. B. phenoxyethyl, naphthoxymethyl, Phenoxypentyl etc,

c) aminoalkyl, ζ. B. aminobutyl, aminoethyl, ammopropyl etc,

d) hydroxyalkyl, ζ. B. hydroxypropyl, hydroxyoctyl, Hydroxymethyl etc,

e) aralkyl, e.g. B. benzyl, phenethyl etc,

f) alkylaminoalkyl, e.g. B. Methylaminopropyl, Me'ihylaminoäthyl etc. and also dialkylaminoalkyl, z. B. diethylaminoethyl, dimethylaminopropyl, propylaminooctyl, etc.,

g) Arylaminoalkyl, e.g. phenylaminoalkyl, diphenylaminoalkyl, N-phenyl-N-ethylaminopentyl, N-phenyl-N-ethylaminohexyl, naphthylaminoethyl etc,

h) nitroalkyl, e.g. B. nitrobutyl, nitroethyl, nitropentyl etc,

i) cyanoalkyl, e.g. B. cyanopropyl, cyanobutyl, cyanoethyl, etc.,

j) haloalkyl, e.g. B. chloromethyl, bromopentyl, Chlorooctyl etc,

k) alkyl substituted with acyl groups of the general formula

- C —R

in which R is hydroxy, hydrogen, aryl, ζ. Β.

Phenyl, naphthyl, etc., lower alkyl of 1-8 carbon atoms, e.g. B. methyl, ethyl, propyl etc. amino including substituted amino, ζ. Β. Di-lower alkylamino, lower Alkoxy of 1-8 carbon atoms, e.g.

Butoxy, methoxy, etc. aryloxy,

an aryl group, e.g. phenyl, naphthyl, anthryl, Fluorenyl, etc. including substituted aryl groups such as

a) alkoxyaryl, e.g. B. ethoxyphenyl, methoxyphenyl, Propoxynaphthyl etc,

b) aryloxyaryl, e.g. B. phenoxyphenyl, naphthoxyphenyl, Phenoxynaphthyl etc,

c) Aminoaryl, e.g. ayninophenyl, aminonaphthyl, Aminoanthryl etc,

d) hydroxyaryl, ζ. B. hydroxyphenyl, hydroxnaphthyl, Hydroxyanthryl, etc.

e) biphenylyl,

f) alkylaminoaryl, e.g. B. Methylarriinophenyl, Methylaminonaphthyl, etc, and also Dialkylaminoary ¹ , z. B. Diethyläminophenyl, Dipropylaminophenyl etc.,

g) arylaminoaryl, e.g. B. phenylaminophenyl, diphenylaminophenyl, N-PhenyNN-ethylaminophenyl, N-phenyl-N-chlofäminophenyl, Nephjhylaminophenyl etc.,

h) nitroaryl, e.g. B. nitrophenyl, nitronaphthyi,

Nitroanthryl, etc.,
i) cyanoaryl, e.g. B. cyanophenyl, cyanonaphthyl,

Cyanoanthryl, etc.,
j) haloaryl, e.g. B. chlorophenyl, bromophenyl,

Chloronaphthyl etc.,
k) an aryl substituted with an acyl group of the general formula

Il

Il
- C —R

in which R is hydroxy, hydrogen, aryl, ζ. Β. Phenyl, naphthyl etc., amino and substituted amino, ζ. B. Di-lower alkylamino, lower alkoxy with 1-8 carbon atoms, ζ. B. butoxy, methoxy, etc., aryloxy, ζ. Β. Phenoxy, naphthoxy etc., lower alkyl with 1-8 carbon atoms, e.g. methyl, ethyl, propyl, butyl etc., is
1) Alkaryl, e.g. tolyl, ethylphenyl, propyl, naphthyl, etc.

(3) a cycloalkyl group with 4 - 8 carbon atoms in the cyclic nucleus, ζ. Β. Cyclobutyl. Cyclohexyl, Cyclopentyl, etc. including substituted cycloalkyl, such as

a) alkoxycycloalkyl, e.g. ethoxycyclohexyl, Methoxycyclobutyl, propoxyclohexyl etc.,

b) aryloxycycloalkyl, e.g. B. phenoxycyclohexyl, naphthoxycyclohexyl, phenoxycyclopentyl in the R is hydroxy, hydrogen, aryl, ζ. Β. Phenyl, naphthyl, etc., amino and substituted amino radicals e.g. B * Di-lower-alkylamino ₍ lower alkoxy with 1 -8 carbon atoms, z> B-butoxy, methoxy etc., aryloxy, ζ. Β.

Phenoxy, naphthoxy, etc. lower alkyl of 1-8 carbon atoms, τ. Β. Methyl, ethyl, propyl, butyl etc.,

(4) a heterocyclic group and substituted heterocyclic group having 5-6 members in Hetero nucleus with at least one sulfur, selenium, oxygen or nitrogen atom, such as one Thienyl group, e.g. B. a benzothienyl group, a pyrrolyl group, e.g. B. a nitropyrrolyl group, a Pyrrolidinyl group, e.g. A pyrrolyl group, a pyrrolinyl group, a benzopyrrolyl group, e.g. B. an indolyl group, a carbazolyl group, a furyl group, e.g. B. a furfuryl group, a benzofuryl group etc., a pyridyl group, e.g. B. a halopyridyl group, an aminopyridyl group, a Hydroxypyridyl group, an alkylpyridyl group, a nitropyridyl group, etc., a piperidyl group, a quinolyl group, an acridinyl group, a pyranyl group, a benzopyranyl group, a Pyrazolyl group, an oxyzolyl group, a thiazolyl group etc.,

(5) hydrogen or

(6) a nitrile group.

etc..

40

Aminocycloalkyl, e.g. B. aminocyclobutyl, aminocyclohexyl, aminocyclopentyl etc,
Hydroxycyloalkyl, e.g. B. hydroxycyclohexyl, hydroxycyclopentyl, hydroxycyclobutyl, etc., arylcycloalkyl, e.g. B. Phenylcyclohexyl, Phenylcyclobutyl etc,

Alkylaminocycloalkyl, e.g. B. methylaminocyclohexyl, Methylaminocyclopentyl etc. and also dialkylaminocycloalkyl e.g. B. Diethylaminocyclohexyl, Dimethylaminocyclobutyl, dipropylaminocyclooctyl etc,

Arylaminocycloalkyl, e.g. B. Phenylaminocyclohexyl, Diphenylaminocyclohexyl, N-phenyl-N-ethylaminocyclopentyl, N-phenyl-N-methylaminocyclohexyl, naphthylaminocyclopentyl etc,

Nitrocycloalkyl, e.g. B. Nitrocyclobutyl, Nitrocyclohexyl, Nitrocyclopentyl etc,
Cyanocycloalkyl, e.g. cyanocyclohexyl, cyanocyclobutyl, cyanocyclopentyl, etc., halocycloalkyl, e.g. B. chlorocyclohexyl, bromocyclopentyl, chlorocyclooctyl etc,
Cycloalkyls substituted with an acyl group of the general formula

65

- C-R

The molecular weight of the polar region polymer is not critical as long as the polymer is in the Composition is present in the amounts indicated above. The material can consist of simple Dimers and trimers up to liquids with medium molecular weight and solid high molecular weight Polymers are made.

Examples of materials with a polar range are given in Table A:

Table A.

Acetonitrile

Propionitrile

Butyronitrile

Oleonitrile

Valeronitrile

2-naphthonitrile

Benzonitrile

Isophthalonitrile

Glycinonitrile

2-aminoproprionitrile

2-amino ~ 4-methylvaleronitrile

1,3,5-pentane tricarbonitrile

5-pyrimidine carbonitrile

1 ^ -Cyclohexandieafbönitfil

4-morpholine acetonitrile

4-pyridine acrylonitrile

2-cyano-3-heptenoic acid

2-cyanoacetamide

2-cyanopropionyl chloride

p-cyanobenzaldehyde

N-cyanomethylphthaHmide

2-hydroxybutyronitrile

Hexanenitrile

3-butenenitrile

Dodecandinitrile

Methacryiniirii

Cyclobutyl nitrile

Hydrogen cyanide

continuation

Acrylonitrile
Nicotinonitrile

Succinonitrile polyacrylonitrile
Poly (methacrylonitrile)
Poly (ben.iacrylonitrile)
Poly-icyclobutyl acrylonitrile)

Poly (pyridyl acrylonitrile) poly ^ (4-pyridine acrylonitrile)
Poly-icyanoacrylonitrile)
Poly (croton nitrile)
Poly (oleonitrile)

Mixtures, blocks, graft and mixed polymers with other vinyl polymers, condensation polymers, silicone polymers and natural resins, as mentioned below under I ₁ II, III and IV.

Thermoplastic Polymers with Dielectric Integrating Factors of less than 0.01 are according to the invention by adding compounds with polar Area, as described above, made sensitive to electromagnetic field energy. Typical thermoplastic polymers that are suitable according to the invention are:

I. Vinyl Polymers Including:

A. Polyolefins from alkene monomers, such as ethylene, propylene, butylene, isobutylene, pentylene and their blends including polyethylene, polypropylene, polyisobutylene, polypentene etc. and copolymers containing alkene monomers including copolymers of Ethylene and propylene, ethylene and butylene, propylene and butylene, terpolymers from Ethylene, propylene, butylene, etc.

B. Polydiolefins from alkadienes such as butadiene, pentadiene, isoprene, chloroprene including Polybutadiene, polyisoprene, polychloroprene and also mixed polymers containing diolefins, such as synthetic rubbers, including SBR, butyl rubber, nitrile rubber, Butadiene acrylic acid rubber, chlorine-containing rubbers,

C. Styrenic polymers including substituted styrenic polymers, halogen-substituted styrenic polymers, alkyl-substituted styrene polymers, mixed polymers of styrene with other vinyl monomers, Olefins and diolefins, ABS polymers, etc.

D. Acrylic polymers, such as poly (alkyl methacrylate), Polyacrylonitrile, polyacrylic acid, polymethacrylic acid, polyacrylamide, copolymers of Vinyl monomers with alkyl methacrylates, etc.

E. polyvinyl esters, such as polyvinyl acetate,

F. polyvinyl alcohol,

G. Polyvinyl acetates, such as polyvinyl formal, polyvinyl butyral etc.

H. chlorine-containing polymers, such as polyvinyl chloride, I. polyvinylamines, such as polyvinyl carbazole, polyvinylpyrrolidones, Polyvinyloxazolidinones, etc.

J. polyvinyl ether,

K. polyvinyl ketones,

L fluorocarbon polymers, such as polytetrafluoroethylene, Polyvinyl fluoride, polyvinylidene fluoride, yinylidene fluoride-hexafluoropropylene copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, Polychlorotrifluoroethylene, etc.,

II. Condensation polymers including polyamides, Polyesters, polyurethane, polyethers, polycarbonates, phenolic resins, amino resins, epoxy resins etc.,

III. Silicone resins,

IV. Natural resins including cellulose polymers, polypeptides, natural rubbers, such as gutta-percha, Balata, Hevea, etc.

V. Mixtures or additives of the aforementioned materials, including mixtures of acrylonitrile-styrene copolymers with an acrylonitrile-butarlien-Styro1-Te ^r -no! ^v mer, of acrylonitrile-styrene copolymers with a butadiene-methacrylonitrile copolymer of an acrylonitrile-alpha-methylstyrene copolymer with an acrylonitrile-butadiene-styrene terpolymer of an acrylonitrile-alpha-methylstyrene copolymer with a butadiene-methacrylonitrile copolymer, etc.

Almost all thermoplastic polymers with dielectric loss factors below 0.01 and practically all of them thermoplastic polymers with dielectric loss factors of 0.009 or less are insensitive for sufficient dielectric heating to make the polymers thermally deformable. That Incorporation of small amounts of materials with a polar region into the thermoplastic polymer causes a polarity of the polymer and thereby an increase in the dielectric loss factor a value at which the polymer is sensitive to various types of dielectric heating. The F i g. 7 and 8 of the accompanying drawings show that increasing amounts of material r'it polar Area in thermoplastic polymers leads to an increase in the dielectric loss factor of the polymer Composition leads The specific polar range used is not critical as long as that Material contains at least one nitrile group, d. H. that the relationships in FIG. 7 and 8 for all materials with a polar region that contain at least one nitrile group included, are the same. The F i g. Figures 5 and 6 of the accompanying drawings show that with increasing dielectric Loss factor is the sensitivity of the thermoplastic polymer to dielectric heating also gets bigger.

The proportion of electromagnetic field energy that is due to the induced movement of the polar Areas (groups) converted into thermal energy is a measure of the dielectric loss factor.

Table B shows, also in tabular form, that small increases in the proportions of material with a polar region lead to an increase in the dielectric loss factor.

Table B.

22 Ol 462

Thermoplastic polymers

Polyethylene (low density)
Polyethylene (low density)
Polyethylene (low density)
Polyethylene (low density)
Polyethylene (low density)
Polyethylene (low density)
Polyethylene (low density)

Poi / ätyrol (impact resistant)
Polystyrene (impact resistant)
Polystyrene (impact resistant)
Polystyrene (impact resistant)
Polystyrene (impact resistant)

Polypropylene
Polypropylene
Polypropylene

The addition of polar range materials, as described above, to thermoplastics Polymers that are responsive to dielectric heating (i.e., to those polymers whose dielectric Loss factors greater than 0.009 or 0.01) increases their sensitivity, making them faster can be heated when subjected to electromagnetic field energy. This feature is economically advantageous because the cycle times are shortened and made faster and cheaper Lead Productivity.

According to a further feature of the invention, a method for dielectric heating is added of thermoplastic films with a thickness of more than 0.13 cm, which have a dielectric loss factor of above 0.003, the unheated sheets of thermoplastic material and backing release agent to one end of a stack of pairs of thermoplastic film and backing release agent and removes one heated film and backing release agent from the other end of the stack of pairs of thermoplastic film and Carrier release agent during each process cycle, each cycle heating the entire Stack covered by heating with radio frequency

Those skilled in the art of radiofrequency heating equipment and its application to materials that have a high dielectric loss factor will readily recognize that the energy absorbed by the heated material depends on its specific heat, mass and the temperature range over which the Material is heated. The heat equation is Q = mc At; Q is the energy; m is the mass; c is the specific heat and At is the temperature differential over which the material is heated. This can be related to the electrical energy consumed by the radio frequency heating device. Knowing the battery current and voltage, assuming "no load" and under process conditions, results in the force requirements that must be calculated for the dielectric material to be heated when the pickling time is fixed. With neglect of thermal losses due to radiation and conductivity of the material to be heated

composition Dielectric Content of material with Loss factor polar range, vol .-% 0 0.0035 2 0.014 3 0.0155 5 0.022 9.15 0.039 13th 0.0505 17.3 0.0650 0 0.0034 1 0.00945 2 0.0142 3 0.0335 5 0.0415 0 0.0035 2 0.0147 5 0.0283

gives the ratio between the thermally absorbed kcal and the consumed electronic Force as:

30th

mc A t _ battery voltage X (load-hours non-load) s-current

When applying the conversion factor of

kcal

3415 · 0.25 ——— = 1 kw, the amount of electroni-S ta.

shear energy can be calculated in the form of radio frequency energy for treating a predetermined Weight amount of plastic material per hour is required.

The amount of heat that can be absorbed per unit of time per kg of material influences the amount of kilowatts of radio frequency units that are required to heat a specific amount of material per hour are. Certain materials have a relatively low "loss factor" and absorb energy at a relatively slow speed, so that the radio frequency energy consumption of the dielectric Heating units can be kept very low. The use of larger systems only leads to the fact that In such systems, fractions of the assumed capacity are used. For optimal process conditions, the plant should be close to the specified Capacity, since the "unloaded" consumption accounts for a significant proportion of the "process load" can be when the system is operated significantly below its real capacity.

For materials with a low loss factor, must the time factor can be increased so that sufficient energy is absorbed per kg of the material to be heated can be. This is usually accomplished by reducing the dwell time in a fixed battery radio frequency heating unit increased or several units connected in series According to the invention, known ones can also be used Method of extending the heating time when continuously heating material or for the semi-continuous sequence of thin and heavy materials used v / ground.

The extension of the heating time for materials with a low dielectric loss factor to the

manner described below is possible according to a preferred feature of the invention. A preferred method for achieving this goal is that, according to a further feature of the Invention the dielectric loss factor is brought to a higher value, which makes it faster Result in heating cycles.

The invention is explained further below with reference to the accompanying drawings Drawings shows

F i g. 1 the flow diagram for thick foils in a dielectric heating device with a fixed anode,

F i g. Figure 2 is the flow scheme for a thin film in a fixed anode dielectric heater;

F i g. 2A shows the heater of FIG. 2 when closed,

3A 3B ₁ and 4 different roads for the continuous treatment of thin films using a conveyor belt with a high loss factor, which moves in contact with non-polar tissue, with the use of stray field of heating,

F i g. 5 shows the dependence of the absorbed energy on the dielectric loss factor of the Resin under the conditions of heating with radic frequency energy,

F i g. 6 shows the dependence of the heating rate on the dielectric loss factor of the Ha.zes under the conditions of heating with radio frequency energy,

F i g. 7 shows the dependence of the concentration of the polar region on the dielectric region in the diagram Loss factor,

FIG. 8 is a diagram similar to FIG. 7, but for different conditions when heating with radio frequency energy,

F i g. 9 in the diagram shows the changes in energy consumption and temperature as a function of the Time during radiofrequency heating.

With reference to FIG. 1 is the heating of heavy foils 0.15-1.27 cm and more with radio frequency energy explained in more detail. A thermoplastic film 1 to be deformed and a sufficient one dielectric loss factor for heating with radio frequencies, is on a film 2 of a Separating means or a carrier film arranged as they are customary in heating systems for radio frequency energy. The carrier film can consist of silicone rubber or tetrafluoroethylene, which has the desired properties has to act as a release agent and are not influenced by the temperatures, as they are usually occur when heating foils for thermal deformation processes. Anyone can do it other material with these properties can be used. The stack of release agent foils and through Radiofrequency to be heated thermoplastic films for thermal deformation is made by suitable Means raised between the radio frequency electrodes 3 and 4, and a non-heated sheet of thermoplastic The material and carrier are placed on the bottom electrode. The upper film 5 and its carrier 6 are Removed From The Stack By Appropriate Means The carrier is then separated from the heated film and reused with unheated foils while the heated foil is in a facility for thermal deformation is transferred, where it is deformed into commercially available objects. The rest of the stack is again placed on top of an unheated foil and support that becomes the top electrode

brought into operating position, if necessary, and radio frequency energy is applied again repeated with carrier and heating of the stack. The unheated foil and the carrier can also be fed to the top of the stack and the heated foils can be peeled off from the bottom of the stack during each cycle. Since the unheated foils are stiffer, it is preferred to introduce the unheated foils at the bottom, as the stack and also the individual sets of foils and carriers can then be handled more easily. The number of sets of foil and carrier detected in a stack depends on the temperature to which the foils must be heated for thermoforming, which in turn depends on the type of plastic material to be heated, the time cycle of the thermal deformation system, the The dielectric loss factor of the foils, the power rating of the radio frequency system and other duration factors depend.
If the use of release agents or supports in the above-described method of electronically heating foils is to be avoided, the stack can be heated to a temperature sufficiently below the melting point to allow one foil to be glued or fused to another in the heating system prevent the hottest individual film in a second Rp.diofrefrequenzheizanlage or another type of heating system for thermal deformation is then heated to the final temperature for thermal deformation. This avoids the need to use and manipulate carriers. Most thermoplastic materials have a greater dielectric loss factor at elevated temperatures so that the heating time for the preheated individual foils can be relatively short compared to the initial heating cycles when passing through the stack in the first heating system. By regulating the number of foils in the first stack, the time for heating the foils in stack form can be coordinated with the time required for further heating of the individual foils in the second heating system so that the foils can be thermally deformed. Under optimal conditions, the thermal deformation cycle is the same as the heating cycle so that a semi-continuous process with maximum production rates can be achieved.

When using films made of thin sheets wound around small-diameter rolls 2 is used to increase the time that the thin films are exposed to radio frequency energy the web 7 is reciprocated back and forth between the radio frequency electrodes 8 and 9. The rollers 10 over which the foils and their carrier films run can be idle or driven rollers

go and be made of a material that absorbs the radio frequency field is not influenced and does not absorb any energy from it

In the case of sufficiently powerful radio frequency devices in which the foils between the electrodes are continuously borrowed at great speed There can be air gaps between the film layers (including the upper and lower Transport film) is available if maximum heating

radio frequency unit speeds with optimal output for the intended application are required and if an intermittent advance of the film through the radio frequency system im The course of the procedure is permitted, the distance between the two plates of a radio frequency system with fixed plates are intermittently narrowed, as shown in FIG. 2A, and then widened again, as shown in FIG. 2 If the two panels are in the open position (far apart), the foil can be used for a a certain length that corresponds to the amount of film to be deformed per cycle Plate spacing is then narrowed whereby the foils are pressed together and the concentration increases polar mass per unit volume between the plates is increased to a practical maximum at which it The radio frequency system enables the maximum amount of energy in the thermoplastic to be heated Convert material into heat. The amount of time to advance a specific length and to Heating multiple layers of thermoplastic Foils should be based on the time cycle of the facility for thermal deformation in conjunction with the radio frequency facility can be set.

As with the heavy cut film method described above, the total area depends of the film subjected to radio frequency heating and the speed with which it passes through the The heating system depends on several factors, namely the temperature to which the film is heated must be, the dielectric loss factor of the film, the performance of the radio frequency system and another. Treatment facility factors and their time cycles.

The treatment lines described above are intended for thermoplastic material on Radio frequency energy responds The carrier films or tapes that serve as conveyor belts are common made of a material that has a low dielectric loss factor and therefore not direct is heated by radio frequency energy. However, it absorbs through heat conduction and radiation substantial amounts of energy from the thermoplastic material being heated. There were different ones Means tries to reduce the radiation loss and conduction loss from the heated thermoplastic To prevent slides from getting onto the conveyor belts, among other things. also preheating the conveyor belts and the application of isolated rooms to reduce heat loss from the conveyor belt to the surrounding area. Such measures reduce the load on the radio frequency system.

The use of conveyor belts 11 and 12 with a large dielectric loss factor is according to the invention Such tapes are also possible at the same time as the polar thermoplastic material on one heated to a certain temperature. An example of this is shown in FIG. 3A shown. When used in conjunction with Insulated rooms can cause heat conduction and radiation to pass through to the conveyor belts Radiofrequency heated thermoplastic material can be reduced or avoided. If you have the dielectric loss factor of the conveyor belts accordingly regulates, one can achieve that the heat from the tape to the thermoplastic to be heated Material flows so that thermoplastic materials with a low dielectric loss factor pass through direct heating of the conveyor belts with high

ίο

is

20th

25th

30th

35

40

45

50

55

60

65 dielectric loss factor can be indirectly heated by radio frequency energy, whereby the thermal energy from the conveyor belts can be transferred to the thermoplastic material through conduction and radiation. The method can be similar to that shown in FIGS. 2 and 2A for thin material can be performed. It should be noted that thick thermoplastic films with low dielectric loss factor (non-polar) can be heated indirectly through carrier films or through plates with dielectric loss factor (polar materials), as described above with regard to the method of FIG. Other geometrical arrangements for the radio frequency electrodes are possible in order to form a compact process plant, as are explained in FIGS. 3B and 4. In Fig. 3B, transverse field electrodes are shown by the "+" and "-" signs, while in Fig. 4 stray field electrodes £ --shows

According to FIG. 3B is the thermoplastic film from a winding roll between two continuous Ribbons 16 and 17 passed through the separating properties and also have a sufficient dielectric Have dissipation factor in order for padiofrequency energy to be sensitive. The tapes enter a thermally insulated space 18 so that they can be circulated in Do not overcool in a closed loop form in a continuous process. That non-polar, thin material is heated by conduction and radiation. The heating rate depends on the temperature of the conveyor belts and the thermal energy contained in the belts, the in turn depends on their thickness, specific heat and the thermal conductivity of the conveyor belts. Properties of the non-polar material, such as thickness, specific heat and thermal conductivity also contributes to the rate of heating of the non-polar material. The percentage of heat absorbed also depends on the contact time between the two materials, which in turn depends on the more intimate Touching the two materials traveled distance and from the speed of movement depends. The temperature to which the non-polar material is heated depends on the thermal Energy from the dielectrically heated conveyor belt towards the as described above heating non-polar material is transferred.

The reasons for the surprising results according to the invention are not known and not yet enlightened. It is believed, however, that each polar region is from a non-polar thermoplastic Polymer is surrounded. The material containing the polar region is easily dielectric heat, while the non-polar material is insensitive to it. Because the polar component is dielectric is heated, a thermal differential is created between it and the surrounding polymer. the The amount of heat conduction across the interface between polar and non-polar material proportional to the contact area and also to the temperature differential, it is further assumed that the heated polar material uses its energy strikes onto the surrounding non-polar material at a rate equal to the temperature differential 4th order corresponds. Under ideal conditions, the speed corresponds with the energy of the polar groups in the electric field is absorbed at the rate at which energy is absorbed by the polar

is transmitted to the non-polar parts of the mass. The useful power is equivalent to an even heating of the total mass by an electrical one Field of radio frequency even if the polymer is insensitive According to this theory is one a disproportionately small mass of polar material capable of a much larger mass of non-polar material Material to heat up in unexpectedly short periods of time when under the influence of an electrical Field (radio frequency)

The invention is further illustrated by the following examples

example 1
Polystyrene

A 32.78 cm ³ sample is produced by mixing high-impact polystyrene with 2% by volume of an acrylonitrile-butadiene elastomer with a content of 35 to 40% acrylonitrile as the material containing the polar region and placed in a dielectric heating system ( 3.5 kW and 22 kV) introduced. The mixture had a mass density of 0.615 g / cm ³ . The sample was then subjected to 100 MHz for 60 seconds. The temperature of the sample before heating was 26.7 ° C and after heating evenly 138 ⁰ C, which corresponds to an increase of about 1 ITC in 60 seconds. Fig. 9 shows the relationship between heating time and temperature or anode current for this example.

Example 2
Polystyrene

Example 1 was repeated except that the volume concentration of the polar region containing material has been increased to 5%. The temperature of the sample rose evenly in the material from 26.7 to over 204 ° C: that is one of over 175 ° C.

Example 3
Comparison with non-polar polystyrene

Example 1 was repeated except that no polar region material was used. After 60 seconds at 100 MHz, there was no noticeable increase in the temperature of the sample. polar area was increased to 10 VoL-Vo. the The temperature of the sample rose steadily from 26.7 to 143 ° C: that is an increase of about 115 ° G

Example 6 Control of polyethylene

Example 4 was repeated except that no polar region material was used. After 60 seconds of treatment at 77 MHz, there was practically no temperature increase in the sample.

Example 7 polypropylene

A 5.5 cm ³ sample was prepared by mixing polypropylene with 2% by volume of acrylonitrile-butadiene polymer containing 35 to 40% acrylonitrile as the polar region material and placing it in a dielectric heater (3.5 kW and 22 kV) introduced. The mixture had a mass density of 035 g / cm ³ . The sample was treated with radio frequency energy of 77 MHz for 60 seconds. The temperature of the sample was 26.7 ° C before heating and was uniformly about 72 ° C after heating. That is an increase of around 45 ° C in 60 seconds.

30th

Example 4
Polyethylene

A 5.5 cm ³ sample was prepared by mixing polyethylene with 52% by volume of an acrylonitrile-butadiene elastomer with a content of 35 to 40% acrylonitrile as a material with a polar range and placed in a dielectric heating system (3.5 kW and 22 kV). The mixture had a bulk density of 0.4 g / cm ³ . The sample was heated by irradiation with radio frequency energy of 77 MHz for 60 seconds. The temperature of the sample before heating was 26.7 ° C and after heating it was uniformly about 93 ° C, that is an increase of over 60 ° C in 60 seconds.

Example 5
Polyethylene

Example 4 was repeated except that the volume concentration of the material was equal to the Example 8 polypropylene

Example 7 was repeated except that the volume concentration of the material was polar Range has been increased to 5% by volume. The temperature of the sample rose steadily from 26.7 ° to 113 ° C: that's a Rise of about 86 ° C.

Example 9 Comparison with non-polar polypropylene

Example 7 was repeated except that no polar region material was used. After 60 seconds at 77 MHz, virtually no temperature rise was observed in the sample

Example 10 Acrylonitrile-butadiene-styrene non-polar resin

A 47 g sample was prepared for the test by injection molding Acrylonitrile-butadiene-styrene polymer with a flow rate of 1.2 g in 10 minutes (ASTM D1238-657) with 1% titanium dioxide in a Banbury mixer mixed, rolled the material into sheets about 0.63 cm thick, which made sheets into granules crushed and produced the test specimen from the granules. The sample was then put into a dielectric Heating system (3.5 kW, 22 kV, 80-100 MHz) installed

A needle pyrometer was placed in the middle of the sample and the temperature rise as a function of the

Time noted. After 60 seconds the temperature was the

Sample increased steadily from 26.7 ° to 90.5 ° C, the

is an increase of about 63 ° C.

Example 11

Acrylonitrile Butadiene Styrene Resin Example 10 was repeated except that

the test sample 2% acrylonitrile butadiene elastomer with a content of 35 to 40% acrylonitrile as a material with polar region contained After 60 Seconds the temperature of the sample had risen steadily from 26.7 ° to over 204 ° C: that is an increase from above 175 ° C.

Example 13

The mixed material of Example 12 was made into films by etWc. 0.63 cm thick rolled and rolled into one 5-fold stacks of 3.18 cm thick folded within 30 seconds after treatment of the Stack with radio frequency energy between 80 and 100 megahertz, the temperature reached a value of 138 ° C based on an initial temperature of 26.7 ° C. That's an increase of around 110 ° C in 30 Seconds.

Table C.

10

15th

Example 14

Example 2 was made with the various polar range materials listed in Table A In each case, the temperature of the sample was compared to similar tested samples that contained no addition with a polar region, significantly increased

As stated above, the addition of Material with polar range does not adversely affect the physical properties of the Product, and in most cases the physical properties are still improved Table C below compares the physical properties of those in Examples 10, 11 and 12 samples described.

example

more polar
area
(Völ-%)

Tensile Elongation Impact Continuous

strengthens (%) strength supple

kg / cm ² cm kg / cm notch (g / 10 min.)

10
11th
12th

0
2
5

357
349
341

46 36 42 35.5
36.5
41.7

1.1
1.2
1.05

According to the invention, thermoplastic resins which are usually based on dielectric heating do not respond electronically to temperatures at or above their thermal deformation and Softening temperatures are heated and processed into finished articles using various processing methods They can be preheated electronically and by pressure, material handling or piston deformation equipment or deformed by forging. They can also be preheated to get the To reduce process costs and to increase production quantities in the case of extrusion and injection molding processes. The mentioned materials with polar range can be found in printing inks, enamel, plastisols and various B-stage resins are entered in order to facilitate the drying or hardening of materials to shorten, which are treated with radio frequency heating systems.

In addition 6 sheets of drawings

Claims (2)

Patent claims: 1. A method for heating thermoplastic polymers with a dielectric loss factor of less than O ₁ Ol by means of electromagnetic field energy for thermal deformation, characterized in that the thermoplastic polymer with 1-20 wt .-% of a material with a polar region with at least ίο mixed with a nitrile group, the mixture obtained is heated by means of radio frequency energy 2. The method according to claim 1, characterized in that the material with a polar Area compounds of the general formula