DE2304403A1 - COVERING FILM MADE OF VINYLIDEN CHLORIDE MIXED POLYMERISATE - Google Patents

Description

KUREHA KAGAKU KOGYO KABUSHIKI KAISHA

Tokyo / Japan

"Wrapping film made of vinylidene chloride copolymer" Priority: January 31, 1972 - Japan No. 10 462/1972

The invention relates to films made of vinylidene chloride copolymer, in particular layered films made from vinylidene chloride copolymer with a low oxygen permeability, one high resistance to cold and weldability to form of tubular films by means of high-frequency welding. In the case of the layer films, one layer film consists of a vinylidene chloride copolymer with a very low oxygen permeability, while the other layer film is made of a vinylidene chloride copolymer with a high softening temperature, 'both films from a multi-layer extruder extruded and then glued together.

In general, the use of vinylidene chloride copolymer films is preferred over numerous other plastic films of other qualities as packaging material for numerous purposes, including food packaging. The films of vinylidene chloride copolymers ^v one expects numerous beneficial effects, such as

309832/0492

the contents of the packaging before rapid destruction, before

Color change or color fading or from oxidation, etc., to protect. . ■

When you consider the protective effect for a color change or color fading the packaged food, then in the case of ordinary minced meat or sausage mass you have it in it affected industrial companies well recognized. that if the wrapping film has oxygen permeability at a temperature

more than '- ₂ , _g

of 30 C of / 10 χ 10 cnr / cm ^{x sec x} Torr, there is insufficient protection against color change and color fading of the packaged meat contents over a long period of time, especially in summer. It is generally assumed that the cause of such a color change and fading is that oxygen, which penetrates the contents from the outside, oxidizes some of the unsaturated fatty acids in the fat to form an o / dicarboxylic acid group, which easily reacts with the amino compounds in the meat protein with the carboxylic acid groups, thereby forming melanoidins, which are the cause of the pale color of the packaged meat product.

As an effective method of improving oxygen impermeability For films made from vinylidene chloride copolymers, in practice certain plasticizers have been selected or the added ones Reduced amount of plasticizer. In addition, other means have been used, such as increasing the vinylidene chloride content in the copolymer and also a reduction in the degree of polymerization of the copolymer obtained by thereby the crystalline portion of the copolymer itself

3 09832/0492

raise.

However, if the aforementioned measures to improve the oxygen impermeability of films made of vinylidene chloride copolymers are used, the flexibility of the film obtained is so reduced that the mechanical strength of the film at low temperature, ie the resistance of the film to low temperatures, is impaired. Particularly in the case of a film with an oxygen permeability at 30 ⁰ C of 3.0 10 ~ ¹² cm ^ / cm χ sec χ Torr and below, a noticeable damage to the wrapping film in the course of the filling of the meat product in the wrapping or during transport would occur. s packaged meat product to the heat sterilization vessel due to insufficient flexibility, it does not allow the speed of the wrapping film to enter / to ensure the mechanical strength of the film at a storage temperature of the meat of usually 5 C or below, so that one consequently

have to accept a lot of waste in the meat product to be packaged.

In view of the difficulties and disadvantages outlined, there are consumer circles for such wrapping films sought films with both a satisfactory oxygen impermeability and a satisfactory one Maintain resistance to cold.

The object of the present invention is therefore to create a film made of vinylidene chloride copolymer which both a low oxygen permeability and a has good resistance to cold. The invention solves this

30 98 3 2/04 92

Task.

The invention therefore relates to a wrapping film, in particular Tubular film, made of vinylidene chloride copolymer with low oxygen permeability and low softening temperature, characterized by at least two layer films of one of which has an oxygen permeability at 30 C of high

■ Ι Λ 7 Q

at least 3.0 χ 10 cm / cm χ sec χ Torr and the other has a softening temperature of at most 20 ° C., the first-mentioned film being in contact with the filler material.

According to a special embodiment, the wrapping film consist of three layer films, the layer film with the low oxygen permeability between two films with the low softening point is arranged.

According to the invention, the wrapping film consists of at least two Layered films with various vinylidene chloride copolymers

e.g.

ten. A vinylidene chloride copolymer contains ^ a smaller one Soft mash content and has an oxygen permeability

- 1 P " ³ VP
of at most 3 * 0 χ 10 "cm / cm χ sec χ Torr. The other vinylidene chloride copolymer has a higher proportion of plasticizers The process is cooled in a cooling medium and then subjected to the action of irrigation air, after which the film formed is wound up on a roll.

30983 2/0492

The film according to the invention can in a simple manner on a conventional continuously operating filling machine with the to packaging contents are filled and then sealed in a high-frequency welding system, which is commercially available.

The one vinylidene chloride copolymer film according to the invention

is characterized by an oxygen permeability of 3 * 0 χ 10

■ ζ O

em / cm χ sec χ Torr and below. The reason for this upper limit is that, even if kneaded meat products with a high fat content such as fish meat, minced meat, pet sausage mass, etc _.; be filled into the cover film produced according to the invention and heat-sterilized, 20 days represent the ultimate limit for protecting the contents of the packaging from a color change or fading in summer.

to a value

The way in which the oxygen permeability of the film / is set below the aforementioned upper limit is either in the selection of the plasticizer to be added to the copolymer or in controlling the amount of plasticizer to be added or in setting the degree of polymerization or the compositional ratio of the polymerizable compounds per se.

The other vinylidene chloride copolymer is characterized by a softening temperature (Tf value) of 20 ^° C. or below,

because this upper limit of the softening temperature of the

with that still
The maximum value is / obtained a film with a cold resistance

30983 2/0492

poured in nm 8.3. / 373

Can be used to protect the wrapping film from breaking while filling the kneaded one kept at 5 ° C or less Meat product or in the course of the transport of the packaged wrapping film for heat sterilization is sufficient.

Such a Tf value can be added by adding a high amount of plasticizer with a good plasticizing effect set for polyvinylidene chloride. Examples of such plasticizers are dibutyl sebacate and dioctyl adipate etc. On the other hand

you can determine the vinyl chloride content in the vinylidene chloride-vinyl chloride copolymer increase so that the crystalline content of the polyvinylidene chloride is reduced, whereby the resulting copolymer becomes flexible.

In this context, however, it should be noted that in the "case of Vinylidene chloride-vinyl chloride copolymer the amount of Vinyl chloride component, which is used to increase the flexibility of the er = -

contributes
holding copolymer / is at most 55 parts by weight.

. With higher amounts, the copolymer begins to harden. In addition, such an increase lowers the Amount of the vinylidene chloride component inevitably affects the gas impermeability of the film obtained and also sets the degree of polymerization and the softening temperature value to a certain extent down.

The wrapping film, which is produced as a tubular film by extrusion the aforementioned two types of copolymers by one

309832/0492

Multi-layer extruder, rapid cooling by means of a quenching agent, Inflation for the purpose of biaxial orientation by means of

Compressed air and winding onto a roll in a folded flat condition can either be in a suitable Can be cut length to provide a four-layer film, or it can be cut into two layers after cutting be separated. In the case of using the split double-layer film, however, it is desirable that the layer in direct contact with the low oxygen permeability with the "filling material comes with a view to protecting the wrapping film from breaking as a result of external influences, and that the layer with the low softening temperature (Tf value) is exposed to the outside.

According to a preferred embodiment, the wrapping film be prepared by dividing the copolymer with the low softening temperature into two parts and the both parts are extruded through two extruder openings, between which the one made of the copolymer with the low oxygen permeability formed film is arranged to form a three-layer film. The type of use for this three-layer Film is the same as that of the aforementioned four-layer film. That is, it is folded flat and wound onto a roll Blown film can be cut to a suitable length and used as a flat film.

The thickness of each film made up of two layers passing through Extrusion of the respective copolymer by a multiple

309832/0492

See-Sextruder, quenching, inflating and winding on a roll are in the range of 3 to 70 microns * A thickness below 3 microns can lead to holes in the film formation should lead to difficulties «. On the other hand, if the thickness exceeds 70 microns, a sufficient cooling effect will not be obtained on the formed film in quenching immediately after extrusion, making it difficult to perform sufficient and uniform stretching orientation by inflation of over 70 microns must therefore not be considered very different from a film under 70 microns in thickness, so that " ¹ a film thickness over 70 microns is not required for practical purposes.

The film thickness of the copolymer with a low softening temperature must preferably be 20 to 70 microns in order to -to deliver satisfactory and favorable results in terms of resistance to cold.

According to the invention to be used yinylidene chloride mixed poly

expedient
merisate consist / consists of 65 to 95 parts by weight vinylidene chloride and from 35 to 5 parts by weight of vinyl chloride "Optionally, acrylic acid, methacrylic acid ,, itaconic acid and their alkyl esters are included in an amount up to 10 parts by weight of _fl to produce a multi-component copolymer"

3 09832/0492

The oxygen permeability of one film must be below 3 # 0 10 "enr / cm χ sec χ Torr, and the softening temperature (Tf value) of the other film must be 20 ° C. or below. These values can be measured as follows:

Oxygen permeability

A film of 5 to 50 microns in thickness is formed from a polymer of a low oxygen permeability "This film is kept 48 hours at a temperature of 5O ⁰ C. Thereafter, the ASTM measured D-14J54 at 30 ⁰ C in accordance with.

Softening temperature (Tf value)

The polymer with a softening temperature of 20 ^° C. and below is melted under pressure. A film 1.0 mm thick is pressed from the melt. This pressed film is kept at a temperature of 50 ^° C. for 48 hours. It is then measured in accordance with ASTM D-1043 «

Example!

To .100 parts by weight of a copolymer obtained by suspension polymerization a monomer mixture made of 80 parts by weight of vinylidene chloride and 20 parts by weight of vinyl chloride becomes 2 parts by weight of epoxidized soybean oil given to produce the first copolymer A.

Furthermore, 100 parts by weight of a copolymer obtained by suspension polymerization of a monomer mixture of > 70 parts by weight of vinylidene chloride and 30 parts by weight of vinyl

309832/0492

Chloride has been produced, 8 parts by weight of sebacic acid dibutyl ester and 2 parts by weight of epoxidized soybean oil, to produce the second copolymer B.

These two copolymers A and B are fed to a double-layer extruder of the type in which two extruder screws are connected to a single nozzle. The copolymers are individually kneaded and melted in the respective extruder. The melts are extruded through the die into a tube shape, quenched with water, blown up with compressed air for a biaxial orientation, then flattened between nip rollers and finally wound up on a roll. A flattened tubular film with a width of 300 mm is obtained. In this film, the part made from the copolymer A has a thickness of 10 microns and the part made from the copolymer B is 40 microns thick. Then both sides of the flattened film are cut lengthways. Then the flattened tubular film is separated into two strips of a double-layer film 96 mm wide,

Each of these double-sided sheets cut off in the aforementioned length is then folded in such a way that the film part with the copolymer A comes to lie on the inside. Then the Edges of the film folded over each other and high-frequency welded. A tubular film with a width of 4.5 mm is obtained in the flat state and a 5 mm wide sealing seam.

For comparison purposes, tubular films 50 microns thick are used

309832/0492

and 43 mm width, measured in the flattened state, by means of a conventional extrusion process using each individual aforementioned copolymers A and B produced. The following investigations are carried out with these three tubular films regarding color change and fading and cold resistance.

(l) testing for color change and -verblassung A mixture of minced fish and meat from _a l 5 parts by weight of chopped haddock, 1.5 parts by weight gehacktsm shark, 0.5 parts by weight of black skin tuna, 5i6 Gewiehtsteilen lumpy red Walfleischs 3.5 Parts by weight of pork fat ^, I ₅ O parts by weight of breadcrumbs _s I ₂ O parts by weight of starch, 3 ^ 0 _{parts by weight of ice water, 2 £} 0 parts by weight of onions, 0.6 parts by weight of table salt, 0.00002 parts by weight of furylfuramide as an antiseptic and 0.002 parts by weight of sorbic acid, =

This mixture, which is kept at a set temperature of 3 ° C., is filled into the three aforementioned tubular films. Both ends of the stuffed with this content wrapping foils warden with Äluminiumdraht hermetically sealed for 60 minutes in 90 ⁰ C hot water dipped for Hitzesterilislerung and then cooled to produce fish hamburger steak. 10 test pieces are made from each of the three wrapping films ".

These test pieces are placed in an incubator kept at 30 ° C left. Observation is carried out with the naked eye.

309832/0492

guided to determine the length of time; until the color of the contents of the package begins to change and fade.

The results show that the double-layer wrapping film according to the invention prevents the meat contents from changing color and fading to a high degree.

The comparison film made from the copolymer A alone is, despite the expectation, that it has the same effect as the one according to the invention double-layer wrapping film would show torn during the filling of the sausage mass, so that it was not rated could be ..

(2) Test for resistance to cold

110 g of water heated to 50 ° C. are poured into a tubular film with a width of% J> mm, measured in the flat state. Both ends of the foil are sealed with aluminum wire. 100 test pieces are made from the three wrapping foils to be examined.

The test pieces are cooled in ice water to 5 ° C and then from a horizontal position from a height of 170 cm onto a hardboard dropped from polyvii ^ lahlorid .. it becomes the extent the damage caused to the wrapping foils as a result of falling due to breakage.

It can be seen from the results given in Table I that the invention has a double-layered wrapping film

309832/0492

shows extraordinarily low levels of damage compared to the wrapping films from the copolymer A alone, all of them are broken »Thus, the films of the present invention show superior cold resistance.

For the sake of comparability, the softening temperature values are also included (Tf) and the oxygen permeability at 30.degree. C. for those produced from copolymers A and B alone Wrapping films listed in Table I.

309832/0492

Table I.

to ο co co

Double-layered
Slide after
the invention '■ Single-layer film (comparison) (B) Color change and fading
after, days 30th (A) 4th Break when falling from 170 cm
ll'ihe in percent 2 (not measurable) 1 Softening temperature
(Tf) ( ⁰ C) <20 100 -8th Oxygen permeability at
30 ° C 3 ₂
(cm / cm «see. Torr) <3.0 x 10 " ¹² 24 -1 p
• 15 X 10 ^{i £ i} C, 8 χ ΙΟ " ¹²

Example 2

80 parts by weight of vinylidene chloride and 20 parts by weight of vinyl chloride are polymerized by a conventional suspension polymerization process. To 100 parts by weight of this copolymer 3 parts by weight of dibutyl sebacate and 3 parts by weight of epoxidized soybean oil are added. One receives a first copolymer C.

To 100 parts by weight of the same suspension copolymer 6 parts by weight of dioctyl adipate, 3 parts by weight of butyl phthalyl butyl glycolate and 2 parts by weight of epoxidized soybean oil to prepare the second copolymer D.

These two copolymers C and D are in a three-layer extruder introduced, in which three extruder screws are connected to a single nozzle. The two copolymers are individually mixed and melted and then made into tubular films extruded through the nozzle in such a way that the film of the first copolymer C is extruded between the two Foils made of the copolymer D come to rest. Then the wrapping film produced is quenched by water, by means of Compressed air inflated for biaxial orientation, then by means of a squeegee; flattened and then on a roll on

wraps. A flattened tubular film with a width of 300 mm is obtained. The film thickness of the inner layer C is 10 microns and the film thickness of the two outer layers D is 10 microns each. Piese flattened film is then on both sides in the longitudinal direction

309832/049 2

cut open. The flattened tubular film is then separated into two strips of three-layer film 96 ram wide.

Each three-layer film cut into the width indicated above is folded once. The edges are then welded to one another by means of high frequency, with a tubular film having a width of} \ J> mm, in the flattened state, with sealing seams 5 ™ wide.

- For comparison purposes, three different tubular Wrapping foils each 50 microns thick and 4j5 mm wide, in the flattened state, by means of the customary extrusion process using the above-mentioned copolymers in each case C or D as well as another copolymer E produced, which by adding 4 parts by weight of adipic acid dioctyl ester, 2 parts by weight of butyl phthalyl butyryl glycolate and 2 parts by weight of epoxidized soybean oil to 100 parts by weight of the foregoing Suspension copolymer has been produced.

These four different wrapping films are subjected to a test for color change in the same way as in Example 1 and subject to fading. The results obtained are shown in Table II.

From this table it can be clearly seen that the inventive three-layer wrapping film compared to comparative films D and E with regard to the protective effect on color change and color fading

30 98 3 2/04 92

23Q4403

solution is superior. Although the effect of the comparative film -C is partly the same as that of the three-layer film according to the invention Wrapping film is formed during the filling of the sausage mass Holes, which is why most of the contents spoil without * the advantages of the wrapping film being able to come into play.

With regard to the cold resistance, the three-layer according to the invention is Film superior to comparison films C and E and essentially the same as comparison film D, just like one 8-day test of the protective effect for a color change and fading shows.

309832/04 92

Table II

O CD 00 CO

Three-shift
Slide after
the invention Single-layer film, (C) (D) (Comparison) Color change and fading
sung after days
-4 25th 26th
(70 % of the sample
pieces wise
Holes open like that
that the contents
within j5 days
is spoiled) 8th
1 (E) Break out when falling
170 cm height in percent β 90 5 15th Softening temperature
(Tf) ( ⁰ C) <20 8th -10 Ί> 9 Oxygen permeability
at 30 ⁰ C (emvcm sec. Torr) '<; 3, o χ ίο " ¹² 2.0 10 ~ ¹² 9.0 χ 10 " ¹² 4 ' 4.5 x ΙΟ ^'12

Claims (5)

Claims before (1. \ Wrapping film, especially in the form of a tubular film, made of vinylidene chloride copolymer with low oxygen permeability and low softening temperature, geke η nzei chnet by at least two layer films, one of which has an oxygen permeability at 30 ° C of at most 3.0 x 10 " crn / em χ sec χ Torr and the other has a softening temperature of at most 20 ⁰ C, the first-mentioned film being in contact with the filler material. 2. Wrapping film according to claim 1, characterized in that it consists of a three-layer film, the one film with the low oxygen permeability between two films is arranged with the low softening point, 3. Wrapping film according to claims 1 or 2, characterized characterized in that the vinylidene chloride copolymer consists of 65 to 95 parts by weight of vinylidene chloride and 5 to 35 parts by weight of vinyl chloride. 4. Wrapping film according to claims 1 to 3. » characterized, that the thickness of each layer film is 3 to 70 microns amounts to. 5. Wrapping film according to claim 1, characterized in that the layer film with the low softening temperature 20 to 70 microns thick. 30983 2/04 92 , '*