CA1115879A

CA1115879A - Destructible marking film, process for its production and method for marking

Info

Publication number: CA1115879A
Application number: CA314,300A
Authority: CA
Inventors: Masao Sahara
Original assignee: Nippon Carbide Industries Co Inc
Current assignee: Nippon Carbide Industries Co Inc
Priority date: 1978-10-26
Filing date: 1978-10-26
Publication date: 1982-01-05

Abstract

ABSTRACT OF THE DISCLOSURE
A destructible marking film having a thickness of about 30 to about 60 microns and a destructibility of not more than 60 kg.cm/mm, said film being composed of a resin composition consisting essentially of (A) 100 parts by weight of a vinyl chloride resin having a degree of polymerization of about 600 to about 2000 and containing 0 to about 5% by weight of a comonomer unit, (B) about 5 to 20 parts by weight of an alkyl meth-acrylate resin which is a blend of an alkyl methacrylate polymer with the alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate polymer with the alkyl group containing 4 to 10 carbon atoms, or a copolymer of an alkyl methacrylate with the alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate with the alkyl group containing 4 to 10 carbon atoms, (C) about 5 to about 30 parts by weight of a liquid plasticizer, (D) about 10 to about 150 parts by weight of a pigment, and (E) 0 to about 10 parts by weight of at least one additive selected from the group consisting of lubri-cants and stabilizers. The film can be prepared by shaping the above-defined resin composition by calendering.

Description

~lS~'79 This invention relates to destructible films which are useful for a wide range of marking purposes, for example as certifying seals, sealing and other labels, decorative or display stickers for motor vehicles and containers, advertisement display stickers used to mark figures and letters on signboards, and various display stickers such as traffic markings, road markings, guide boards, danger warning markings and markings on merchandizeO
For use in these applications, marking films are required to have suitable destructibility whereby a break occurring in one part doe~ not extend to the surrounding other part. In addition, they should desirably possess good opera-bility in an operation of bonding to a substrate, good thermal stability, ease of m--nufacturing operation, low cost, environ-mental safety during manufacture, good productivity, good surfacesmoothness, and good reproducibility of qualityO
~ he present invention relates to destructible marking films having good operability in an operation of bonding to a sub~trate, good thermal stability, ease of manufacturing operation, low cost, environmental safety during manufacture, good productivity, good surface smoothness and good reproducibility of destructibility.
Specifically, the present invention provides a destructibl~ marking film having a thickness of about ~0 to about 60 microns and a destructibility of not more than 60 kg.cm/mm, said film being composed of a resin composition consisting essentially of (A) 100 parts by weight of a vinyl chloride resin having a degree of polymerization of about 600 to about 2000 _ ~ _ ~k 1~15~3'7~

and containing 0 to about 5% by weight of a comonomer unit, (B) about 5 to about 20 parts by weight of an alkyl methacrylate resin which is a blend of an alkyl methacrylate polymer with the alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate polymer with the alkyl group containing 4 to 10 carbon atoms, or a copolymer of an alkyl methacrylate with the alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate with the alkyl group containing 4 to 10 carbon atoms, (C) about 5 to about 30 parts by weight of a liquid plasticizer, (D) about 10 to about 150 parts by weight of a pigment; to a pro-cess for producing said destructible marking film by calendering; and to a method of marking a substrate by applying to the surface of the substrate said destructible marking film.
The film can also contain up to 10 parts by weight of an additive which is a lubricant or stabilizer.
Destructible films for marking have heretofore been produced solely by a casting method (coating method). This is firstly because conventional destructible marking films are ultrathin films with a thickness of less than about 70 microns, usually up to about 30 microns. If it is desired to form such a thin and substantially unstretched film by a melt-extrusion method, there is no choice but to adopt an extremely slow extruding speed. As a re-sult, thickness unevenness occurs considerably. Furthermore, the film natur-ally undergoes heat decomposition over an extended period of time, and its deterioration cannot be avoided. Such a method is never commercially feas-ible.
Secondly, when it is desired to form such an ultrathin, substantial-ly unstretched film by a calender method, the roll-separating force increases.
The roll pressure should therefore be reduced drastically, and an extreme decrease in the speed of production cannot be avoided. It is actually impos-sible ~15879 for this method to give an ultrathin film having substantially no directionality and a uniform thickness~
If, therefore, it is desired to obtain an ultrathin film by the melt-extruding or calendering method, the resulting film must be made thinner by a stretching operation. ~he stretched films, however, are not acceptable as destructible marking films.
The production of destructible marking films has many disadvantages including poor operability in a bonding operation, poor thermal stability, the complexity of the manufacturing operation, the high cost of production, poor safety of the working environment associated with the use of ~olYent, the necessity of recovering the solvent, low produc-tibility, poor surface smoothness (formation of pockmark-like spots) ascribable to the volatilization of the solvent, and the difficulty of adjusting the destructibility of the film to the desired one.
The present inventors made investigations in order to provide destructible marking films and a process for their production, which are free from the defects of conventional de~tructible marking films and conventional methods for their production. These investigations have led to the surprising discovery that by using a pigment-containing resin composition comprising specified ~roportions of a vinyl chloride resin, an alkyl methacrylate resin, and a liquid plasticizer, preferabl~ further containing a lubricant or stabilizer, substantially unoriented destructible marking films having a very uniform thickness can be produced by a calender method at feasible speeds of production without causing any of the l~lS879 disadvantages of the prior art described hereinaboveO
It is an object of this invention therefore to provide an ultrathin destructible calender film for marking which is far superior to conventional products~
Another object of this invention is to provide a process for producing this new and excellent destructible marking film.
Still another object of this invention is to provide a method for marking using such a destructible marking filmO
Other objects and advantages of this invention will become more apparent from the following description.
The destructible film of the invention has a des-tructibility, as measured by a punch-type impact testing method, of not ~ore than 60 kg.cm~mm, preferably about 2 to 15 about 25 kg.cm~mm, more preferably not more than about 15 ; kg.cm/mmO
~he destructible marking film of the invention is an ultrathin calender film having a thickness of about 30 to about 60 microns which is composed of a pigment-containing resin composition containing 100 parts by ~eight of a vinyl chloride resin having a degree of polymerization of about 600 to about 2000 and optionally containing not more than about 5% by weight of a comonomer component, about 5 to about 20 parts by weight of an alkyl methacrylate resin, and about 5 to about 80 parts by ~-eight of a liquid plasticizerO ~he above pigment is contained preferably in an amount of about 10 to 150 parts by weight per 100 parts by weight of the vinyl chloride resinO The destructible marking film of this invention also preferably contains about 1 to about 10 parts ~lS879 by weight of a lubricantO ~urthermore, the destructible marking film of this invention may contain a stabilizer in an amount o~ up to about 10% by weight per 100 parts by weight of the vinyl chloride resinO
The vinyl chloride resin used in this invention has a degree of polymeri~ation of about 600 to about 2000, prefer-ably about 600 to about 16000 If its degree of polymerization is less than about 600, the film becomes too brittle and has poor operability in bondingO Moreover, its thermal stability also becomes inferiorO On the other hand, if its degree of polymerization exceeds about 2000, the productibity is reduced, and production at commercially feasible speeds is impossibleO
~he vinyl chloride resin may contain up to about 5% by weight of a comonomer component such as ethylene, propylene, butene, vinyl acetate, an alkyl acrylate, vinylidene chloride, a vinyl ester or a vinyl etherO
The alkyl methacrylate resin used in the invention includes, for example, mixtures of al~yl methacrylate polymers with the alkyl group containing 1 to 3 carbon atoms and alkyl methacrylate polymers with the alkyl group containing 4 to 10 carbon atoms, and copolymers of alkyl methacrylates with the alkyl group containing 1 to 3 carbon atoms and alkyl methacrylates with the alkyl group containing 4 to 10 carbon atomsO
If the amount of the alkyl methacrylate resin is too small, the productivity is markedly aggravated, and the resulting film has an unsatisfactory destructibilityO On the other hand, if it is too large, the film is brittle, has poor chemical resistance and loses its utilityO
The destructible marking film of this invention also ~5~79 contains a liquid plasticiæer in an amount of about 5 to about 80 parts by weight per lO0 parts by- weight of the vinyl chloride resinO Specific examples of the liquid plasticizer include phthalic acid derivatives such as dimethyl phthalate, diethyl phthalate, ~ibutyl phthalate, di-(2-ethylhexyl) phthalate, di-n-octyl phthalate, esters formed between higher alcohols and phthalic acid, diisooctyl phthalate, diisobutyl phthalate, dipentyl phthalate, diisodecyl phthalate, ditridecyl phthalate, diundecyl phthalate, di(heptylnonylundecyl) phthalate, benzyl phthalate, butyl benzyl phthalate, dinonyl phthalate, di-n-alkyl phthalates, and di-n- (or iso-)alkyl phthalate 8;
isophthalic acid derivatives such as dimethyl isophthalate, di-(2-ethylhexyl) isophthalate and diisooctyl isophthalate;
tetrahydrophthalic acid derivatives such as di-(2-ethylhexyl) tetrahydrophthalate, di-n-octyl tetrahydrophthalate, diisodecyl tetrahydrophthalate, and C7-ClO alkyl tetrahydrophthalates;
adipic acid derivatives such as di-n-butyl adipate, di-(2-ethylhexyl~ adipate, diisodecyl adipate, benzyl octyl adipate and di-(butoxy ethoxy ethyl) adipate; azelaic acid derivatives such as di-(2-ethylhexyl) azelate, diisooctyl azelate and di-2-ethylhexy1-4-thioazelate; sebacic acid derivatives such as di-n-butyl sebacate and di-(2-ethylhexyl) sebacate; maleic acid derivatives such as di-n-butyl maleate, dimethyl maleate and diethyl maleate; fumaric acid derivatives such as di_ n-butyl fumarate and di-(2-ethylhexyl) fumarate; trimellitic acid derivatives such as tri-(2-ethylhexyl) trimellitate, tri-n-octyl trimellitate and triisodecyl trimellitate; citric acid derivatives such as triethyl citrate, tri-n-butyl citrate and acetyl triethyl citrate; itaconic acid derivatives such ~15879 as monomethyl itaconate, monobutyl itaconate and dimethyl itaconate; oleic acid derivatives such as butyl oleate, tetrahydrofurfuryl oleate and glyceryl monoleate; ricinoleic acid derivatives such as methyl acetyl ricinolate, butyl acetyl richinolate and glyceryl monoricinolate; stearic acid derivatives such as n-butyl stearate, glyceryl monostearate and diethylene glycol distearate; and other compounds, for example diethylene glycol monolaurate, benzenesulfonic acid butylamide, trimethyl phosphate, tributoxyethyl phosphate, tetra-2-ethylhexyl pyromellitate, diethylene glycol dibenzoate, glycerol monoacetate, chlorinated paraffin, epoxy derivatives with an oxirane oxygen content of 2 to ~/0 and a molecular weight of not more than 1000, and polyesters with a molecular weight of at least 1000 derived from sebacic acid, adipic acid, azelaic acid, or phthalic acid9 When the amount of the liquid plasticizer is smaller than the specified limit, the resulting film is unsatisfactory in its operability in a bonding operationO When its amount exceeds the specified upper limit, the resulting film is unsuitable because of the loss of destructibility and poor dimensional stabilityO
The destructible marking film of the invention further contains a pigmentO The amount of the pigment is not strictly limited, but especially good results are obtained when it is used in an amount of about 10 to about 150 parts by weight per 100 parts by weight of the vinyl chloride resinO
Examples of the pigment include inorganic pigments such as titanium oxide, zinc oxide, lead white, calcium carbonate, gypsum, precipitated silica, carbon black, red iron oxide, 1~5879 molybdenum red, cadmiu~ yellow, yellow lead, titanium yellow, chromium oxide green and ultramarine; and organic pigments such as Permanent Red 4R, Hansa Yellow lOG, Benzidine Yellow GR, Permanent Carmine FB, Phthalocyanine Blue B and Phthalo-cyanine Green~
Preferably, the destructible marking film of theinvention further contains up to about 10% by weight, par-ticularly about l to about lO parts by weight of a lubricant per lO0 parts by weight of the vinyl chloride resinO Almost all lubricants usually employed in the processing of vinyl chloride resins are also feasible in the present invention~
For example, there can be used polyethylene waxes, liquid paraffin, stearic acid, stearamide, bisamide, n-butyl stearate, and aliphatic alcohols. ~he lubricant serves to increase the dimensional stability of the marking film of the invention after bonding, and frequently produces favorable resultsO
The marking film of the invention may further contain B a small amount of ahs ~bilizer in an amount of up to about lO parts by weight per 100 parts by weight of the vinyl chloride resin. Specific examples of the stabilizer are calcium stearate~
barium stearate, lead stearate, monobasic lead sulfite, dibasic lead sulfite, dibutyltin dilaurate, dibutyltin dimaleate, dibutyltin mercaptide, dioctyltin maleate-type stabilizers, dioctyltin laurate-type stabilizers, dioctyltin mercapto-type stabilizers, stannane diol derivatives, mixtures of these, and nonionic surface active agents such as polyoxyethylene, glycerin monostearateO
The destructible marking film of the invention can be produced by calendering the pigment-containing composition _ 9 _ >~

1~15879 containing the aforesaid ingredients to form a film having a thickness of about 30 to about 63 micronsO The operation of forming films by the calender process is well known, and the same operation can be used in the present inventionO In the present invention, it is preferred that the film which has been formed by a calender machine be quenched with a gaseous cooling medium such as air, nitrogen or carbon dioxide at not more than 30C, for example, at about -lO to about 30C at its necking portion.
Since the film of the invention is a destructible marking film, it is imperative to avoid an operation of forming an ultrathin film by stretching the film to an extent such that the destructibility (impact sterength) of the film exceeds 60 kgo cm/mm. Thus, the calendering should be performed so that the film as-formed has a thickness of about 30 microns to about 60 microns. When a stretching action is to be exerted on the as-formed film, the stretch ratio should desirably be limited to not more than about 5~o, preferably to not more than about ~0%, in terms of the percentage of the surface linear speed of film take-up rolls based on the surface linear speed of film deli~ery rolls. The calendering temperature is about 14 to about 190C, and the temperature at the time of stretching described above is about 50 to about 140Co According to the present invention, the use of the pigment-containing resin composition having the specified constituents and proportions described hereinabove makes it possible to commercially produce destructible marking films of good quality by a calender method which has not been utilized heretofore in the production of destructible marking films.

_ 10 --~15~79 The provision of such ultrathin destructible calender films for marking purposes has completely overcome the disadvantages of destructible films prepared by the conventional casting methodO
The foll~wing examples illustrate the present in-vention more specifically.
xample 1 ~ormulation Parts b~_wei~ht Polyvinyl chloride having a degree of polymeri~ation of 1600 100 Copolymer of pentyl methacrylate/methyl methacrylate (10/5) 15 Di-(2-ethylhexyl) phthalate 15 Titanium oxide 50 Tin-type stabilizer 2 Polyethylene wax 2 A composition of the above formulation was shaped by a calender method under the following conditions, and cooled with air at 25C to form a film having a thickness of 50 micronsO
~he temperatures of the various rolls used in t~e calender method were as follows:
Mixing roll: 175C
Warming roll: 175 Calender rolls Rl: 175 R2: 170 R3: 165 R4: 160 The stretch ratio of the film was 15%o ~ 11 ~

1~15B79 Example 2 Formulation Parts b~ wei~ht Polyvinyl chloride having a degree of polymerization of 1100 lO0 Copolymer of n-butyl methacrylate and methyl methacrylate (4/2) 6 Di-(2-ethylhexyl) adipate 15 ~poxidized soybean oil 5 Titanium oxide 20 Lead-type stabilizer 3 Stearamide A composition of the above formulation was shaped by a calender method under the following conditions, and cooled with air at 10C to form a film having a thickness of 60 micronsO
All the rolls were kept at 170C during the shaping, and the stretch ratio of the film was 10%u Example 3 Formulation Parts b~ wei~ht Copolymer of vinyl chloride with 3% of propylene having a degree of polymerization of 800 lO0 Copolymer of 2-ethylhexyl methacrylate and ethyl methacrylate (15/4) 19 Adipic acid-derived polyester 7 Phthalocyanine Blue 5 ~ight calcium carbonate lO
Barium-zinc type stabilizer 4 Bisamide 4 A composition of the above formulation was shaped by a calender method under the following conditions, and ~S 15~79 cooled with air at 10C to form a film having a thickness of 40 microns.
The temperatures of the various rolls used in the calender method were as follows:
Mixing roll: 170C
Warming roll: 170 Calender rolls Rl: 170 R2: 170 R3: 175 R4: 180 The stretch ratio of the film was 20%.
Comparative ~xample 1 Example 1 was repeated except that the stretch ratio of the film was changed to 100%.
Comparative Example 2 A composition of the same formulation as in Example 1 was cast into a film having a thickness of 50 microns. A
solvent consisting of methyl ethyl ketone and toluene in a ràtio of 80:20 was used, and the composition was cast on a 80 m-long stainless steel belt, and dried in an atmosphere kept at 80 to 160C. No cooling was performed. ~he stretch ratio of the film was 5Yo.
Com~arative Example 3 ~ormulation Parts by wei~ht Polyvinyl chloride having a degree of polymerization of 1600 100 Copolymer of pentyl methacrylate and methyl methacr~late (20/8) 28 1~15Y,'~9 Di-(2-ethylhexyl) phthalate 15 ~itanium oxide 50 ~in-type stabilizer 2 Polyethylene wax 2 Except using a composition of the above formulation, the ~ame procedure as in ~xample 1 was repeatedO
Com~arative ExamPle 4 ~ormulation Parts b~ wei~ht Polyvinyl chloride having a degree of polymerization of 1100 100 Cspolymer of n-butyl methacrylate and methyl methacrylate (3/1) 4 ~i-(2-ethylhexyl) phthalate15 ~poxidized soybean oil 5 Titanium oxide 50 Lead-type stabilizer 30 Stearamide A composition of the above formulation was shaped by a calender method under the same conditions as in ~xample

2 to form a film having a thickness of 60 microns~
Comparative ~xample 5 A composition of the same formulation as in Comparative Example 4 was used except that 35 parts by weight of dioctyl phthalate was used instead of the dioctyl phthalate and epoxidized soybean oil. ~he composition was calendered under the same conditions as in ~xample 1 Comparative ~xample 6 Formulation Parts b~ wei~ht Copolymer of vinyl chloride and 18% by weight of vinyl acetate having a degree of polymerization of. 600 100 _ 14 -1~15879 Copol~er of n-butyl methacrylate and methyl methacrylate (1~/5~ 15 Di-(2-ethylhexyl) phthalate 20 Titanium oxide 110 Stearic acid 005 A composition of the above formulation was cast into a film having a thickness of 50 microns under the same conditions as in Comparative Example 2.
The various properties of the films obtained in these ~xamples and Comparative Example.s were measured by the following methods, and the results are shown in Table 1.
Destructibilit~
Measured at 25C by a film impact tester (capacity 30 kg.cm, impact speed 2.2 km/sec., an impact ball with a radius of 1 inch) in accordance with a punch-type impact testing method.
Operabilit~ in bondin~
The operability is evaluated by the height of the head of a rivet with a di~leter of 10 mm to which the film coated with an adhesive can be applied without breakage or rising.
1: a height of more than 4 mm 2: a height of 4 to 3 mm

3: a height of 3 to 2 mm

4: a height of 2 to 1 mm

5: a height of less than 1 mm The larger the height, the better the operability.
Thermal stabilit~
~he film, white in color, bonded to an aluminum plate l~lSB79 is allowed to stand in a Geer's oven at 150C for 40 minutes.
It is then taken out of the oven, and its color is evaluated on a scale of 1 to 4 as follows:
1: no change in color 2: changed to light pink 3 changed to light violet 4: changed to violet This chan~e in color is especially significant when the film is intended for application to parts requiring thermal stability, for example to an engine compartment of an automobile.
Surface smoothness Ten squares (10 x 10 cm) were drawn at random on the film. Light is applied from below the film, and the number of points having high light transmittance present in each square 1~ is visually countedO The smoothness is evaluated by the total number of such points in the ten squares.
Microscopic examination shows that these points are depressed like pockmarks. These depressed points are very significant because they may cause ink skip when the film is printed.
Productivit~
The maximum speed at which the film can be produced without the occurrence of defects.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A destructible marking film having a thickness of about 30 to about 60 microns and a destructibility of not more than 60 kg.cm/mm, said film being composed of a resin composition comprising:
(A) 100 parts by weight of a vinyl chloride resin having a degree of polymerization of about 600 to about 2000 and containing 0 to about 5% by weight of a comonomer unit, (B) about 5 to about 20 parts by weight of an alkyl methacrylate resin, which is a blend of an alkyl methacrylate polymer with the alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate polymer with the alkyl group containing 4 to 10 carbon atoms, or a copolymer of an alkyl meth-acrylate with the alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate with the alkyl group containing 4 to 10 carbon atoms, (C) about 5 to about 30 parts by weight of a liquid plasticizer, and (D) about 10 to about 150 parts by weight of a pigment.

2. The film of claim 1 wherein the comonomer unit of resin (A) is selected from the group consisting of ethylene, propylene, butene, vinyl acetate, alkyl acrylates, vinylidene chloride, vinyl esters and vinyl ethers.

3. The film of claim 1 which additionally contains up to 10 parts by weight of at least one additive selected from the group consisting of lubri-cants and stabilizers.

4. A process for preparing a destructible marking film having a thick-ness of about 30 to about 60 microns and a destructibility of not more than 60 kg.cm/mm, which comprises shaping a resin composition by calendering, said resin composition consisting essentially of (A) 100 parts by weight of a vinyl chloride resin having a degree of polymerization of about 600 to about 2000 and containing 0 to about 5% by weight of a comonomer unit, (B) about 5 to about 20 parts by weight of an alkyl methacrylate resin, which is a blend of an alkyl methacrylate polymer with an alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate polymer with an alkyl group containing 4 to 10 carbon atoms, or a copolymer of an alkyl methacrylate with an alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate with an alkyl group containing 4 to 10 carbon atoms, (C) about 5 to about 30 parts by weight of a liquid plasticizer, and (D) about 10 to about 150 parts by weight of a pigment.

5. A method for marking, which comprises applying to the surface of a substrate a destructible film having a thickness of about 30 to about 60 microns and a destructibility of not more than 60 kg.cm/mm, said film consist-ing essentially of (A) 100 parts by weight of a vinyl chloride resin having a degree of polymerization of about 600 to about 2000 and containing 0 to about 5% by weight of a comonomer unit, (B) about 5 to about 20 parts by weight of an alkyl methacrylate resin, which is a blend of an alkyl methacrylate polymer with an alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate polymer with an alkyl group containing 4 to 10 carbon atoms, or a copolymer of an alkyl methacrylate with an alkyl group containing 1 to 3 carbon atoms and an alkyl methacrylate with an alkyl group containing 4 to 10 carbon atoms, (C) about 5 to about 30 parts by weight of a liquid plasticiser and (D) about 10 to about 150 parts by weight of a pigment.