JPH03175035A - Polyester resin laminated film - Google Patents

Abstract

PURPOSE:To obtain a laminated film having excellent thermal adherence by providing a thermal adhesive layer consisting of specific different two kinds polyester on the surface of a base material film consisting of polyester resin. CONSTITUTION:The polyester resin laminated film is of a type having a base material film consisting of polyester resin, and a thermal adhesive layer provided at least on one face of the base material film and comprising a resin composi tion consisting mainly of polyester A and polyester B. The polyester A contains at least one kind of glycol component shown in formula I and the polyester B contains respectively at least one kind of dicarbonic acid component shown in formula II - a and glycol component show in formula II - b, and the polyester A and polyester B are contained in the composition at the weight ratio of (80 : 20) - (50 : 50). In the formulas, the R1 and R2 are selected from by drozen and a 1-6C alkyl group, and at least either one of them is a 1-6C alkyl group, and further (n) and m are each integer of 1 - 6. And, (p) is an integer of 4 - 10, and (q) is an integer of 4 - 20.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention has excellent thermal adhesion (heat sealability) and the thermally bonded portion can be easily opened, making it suitable for use as food packaging films and various industrial films. This invention relates to a useful polyester resin laminate film.

(Prior art) Polyester resin films (hereinafter, the term "film" is also used to include sheets) have mechanical strength, heat resistance, cold resistance, chemical resistance, insulation, dimensional stability, flatness, and transparency. It has excellent adhesive properties and is used for a variety of purposes such as packaging films, insulation tapes, photographic films, and tracing films.In particular, it has thermal adhesive properties for packaging various products including food. Polyester-based resin films have become widely used.When packaging food, they have the property of not emitting odors, not impairing food aromas, and not easily adsorbing food odors (i.e., flavor resistance). Polyester resin films having a and a thermal adhesive layer (sealant layer) made of a resin with a lower melting point on its surface.
are formed by coating, coextrusion, etc. For example, JP-A-63-17048 discloses a method of forming a thin layer of a composition obtained by mixing a thermoplastic polyester resin with a melting point of 80 to 200°C and a polyolefin resin on at least one side of a polyester base film. Disclosed. However, in this method, the compatibility between the polyester resin and the polyolefin resin is insufficient, so the resulting laminated film has low transparency. Furthermore, since the adhesive strength is not sufficient, it is necessary to increase the thickness of the thermal adhesive layer. In addition, when the amount of polyolefin resin increases, the adhesive force between the base film and the thermal bonding layer decreases,
and poor flavor resistance.

From the above, when a polyester resin is used for the base film, it is considered preferable to also use the polyester resin for the thermal adhesive layer.

For example, 1.4-
A thermal adhesive layer is formed using a polyester-based resin having a heat of crystal fusion of 5 cal/g or less, which contains a polyester consisting of butanediol and/or 1,6-benzenediol and terephthalic acid and/or isophthalic acid. This has been disclosed. According to this method, since the glass transition point of the thermal adhesive layer is lowered, the film adheres to the nip roll during film formation, resulting in a decrease in the winding properties of the film. Furthermore, when this film is processed into a bag shape,
Adhesion (blocking) between adhesive layers is likely to occur. JP-A-63-15745 discloses a thermoplastic polyester containing 95 mol% or more of tele, phthalic acid and/or isophthalic acid as a dicarboxylic acid component and having a glass transition point within the range of 50 to 80°C. A laminated film is disclosed in which a thin layer consisting of the following is formed on at least one side of a base film. In such a laminated film, it is difficult to open the sealed portion after thermal bonding, and the base film is easily torn. In other words, the seal part does not have tough properties. Here, "tough" refers to properties that have sufficient strength and durability, and are not flexible or brittle. If the seal part is not tough, e.g.
When the entrance of a bag is closed with heat adhesive, if you try to open the bag by pinching the mouth of the bag with your fingers and pulling it open, the seal may not peel off cleanly and break in the middle, or the bag may open without being peeled off sufficiently. The disadvantage is that the body of the device can tear in undesirable directions.

(Problems to be Solved by the Invention) The present invention is intended to solve the above-mentioned conventional problems, and its purpose is to have excellent thermal adhesion properties and to have tough properties in the sealed portion after thermal adhesion. In other words, it has high strength,
And when peeling off the seal part, the stress concentrates on a specific part and the seal part breaks in the middle, so it can be easily peeled off by just applying a moderate amount of force). It is about providing.

(Means and effects for solving the problems) The polyester resin laminated film of the present invention comprises a base film made of a polyester resin, and polyester A and polyester B provided on at least one side of the base film.
A polyester resin laminate film having a thermal adhesive layer made of a resin composition having as a main component, the polyester A containing at least one glycol component represented by the following formula (I), and the polyester B containing at least one glycol component represented by the following formula (I). , the following formula (II-a
) and at least one glycol component represented by the following formula (■-b), and the polyester A and the polyester B contain 80:
It is contained in the composition in a weight ratio of 20 to 50:50, thereby achieving the above objectives: 1. HO-(CH2). -C-(CH2)I-OH(I)
2 Here, R1 and R2 are selected from hydrogen and an alkyl group having 1 to 6 carbon atoms, at least one of which is an alkyl group having 1 to 6 carbon atoms, and n and m are integers of 1 to 6, HOOC-(CH2)ri-COOH(II-a) where p is an integer from 4 to lO, HO-(CH2)q-OH(II-b) where q
is an integer from 4 to 20.

Examples of the polyester resin constituting the base film of the laminated film of the present invention include polyesters such as polyalkylene terephthalates such as polyethylene terephthalate and polybutylene terephthalate; polyalkylene terephthalates such as polyethylene naphthalate; A system polymer, a mixture thereof, or a copolymer whose main component is a constituent monomer component of these resins is used. The base film may contain various additives in addition to such a polyester resin. Examples of additives include antistatic agents, lubricants, antifogging agents, plasticizers, stabilizers, antiblocking agents, and colorants. The base film is preferably a uniaxially stretched film or a biaxially stretched film.

It is desirable that the polyester resin which is the main component of the resin composition used for the thermal adhesive layer of the laminated film of the present invention has the following properties: a) has affinity with the polyester resin film that is the base material; b) A suitable adhesive so that when the obtained laminated film is thermally bonded, the bonded portion maintains tough properties and the concentration of stress on a specific portion is avoided when the bonded portion is peeled off. and C) so that it is easy to prepare a laminated film.
It must be soluble in industrially common solvents, or it must be easy to melt extrude.

The resin composition used in the present invention satisfies these conditions and comprises polyester A having a glycol component represented by the following formula (I) and a dicarboxylic acid component represented by the following formula (II-a). and polyester B having a glycol component represented by the following formula (II-b); Here, R1 and R2 are hydrogen and a carbon number of 1
~6 alkyl groups, at least one of which is an alkyl group having 1 to 6 carbon atoms, and n and m are 1 to 6 alkyl groups.
is an integer of 1100cm(CH2)I)-COOH(If -a
) Here, p is an integer of 4 to 10, HO-(CH2)Q-OH(■-b) Here, q is an integer of 4 to 20.

Glyfur components of formula (I) contained in polyester A include 2,2-dimethyl-1,3-propanediol, 2-methyl-2-ethyl-1,3-propanediol, and 2-methyl-2- Propyl-1,3-propanediol, 2-methyl-2-isopropyl-1,3-propanediol, 2-methyl-2-butyl-1,3-propanediol, 2-methyl-2-n-hexyl-1 ,3-
Propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-n-butyl-1,3-propanediol, 2-ethyl-2-n-hexyl-1,
3,-propanediol, 2,2-di-n-butyl-1
, 3-propanediol, 2-n-butyl-2-propyl-13-propanediol, 2,2-di-n-hexyl-1,3-propanediol, 2-n-phthyl-1.
3-7'ropanediol, 2-n-propyl-1,3-
Propanediol, 2-ethyl-1,4-butanediol, 2-methyl-2-ethyl-1,4-butanediol, 3-methyl-1,5-bentanediol, 3,3-dimethyl-1,5- Bentanediol, 3-n-propyl-1,5-bentanediol, 6-methyl-1,12-
These include dodecanediol. These glycol components account for 5 mol% or more of the total glycol components,
It is preferably contained in a proportion of 10 mol% or more.

As the glycol component other than the compound of formula (I) contained in polyester A, ethylene glycol is most preferable. If the amount is small, diethylene glycol, propylene glycol, butanediol, hexanediol, or 1,4-cyclohexane dimetatool may be used.

As the dicarboxylic acid component contained in polyester A, terephthalic acid is most preferred. If the amount is small, a dicarboxylic acid component may be added for copolymerization. As other dicarboxylic acid components, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, and azelaic acid; aromatic dicarboxylic acids such as isophthalic acid, diphenyldicarboxylic acid, and 2,6-naphthalene dicarboxylic acid are used.

The dicarboxylic acid component of the formula (If-a) contained in polyester B includes adipic acid, azelaic acid, sebacic acid, pimelic acid, speric acid, undecanoic acid, dodecanedicarboxylic acid, brassic acid, tetradecanedicarboxylic acid, tabucic acid. , nonadecanedicarboxylic acid, tocosandicarboxylic acid, etc., and adipic acid, azelaic acid and sebacic acid are particularly preferred. These dicarboxylic acids usually account for 5 to 50% of the total dicarboxylic acids in polyester B.
It is contained in a proportion of mol %, preferably 10 to 40 mol %.

Polyester B may contain other dicarboxylic acid components in addition to the compound of formula (II-a). These include, for example, aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalene dicarboxylic acid, or alicyclic dicarboxylic acids such as cyclohexadicarboxylic acid; It is preferable that at least one of them is contained. A particularly preferred dicarboxylic acid component is terephthalic acid.

The glycol component represented by the formula (II-b) contained in polyester B includes butanediol, bentanediol, hexanediol, and the like.

These glycols are contained in a proportion of 10 mol% or more, preferably 30 mol% or more, and more preferably 50 mol% or more of the total glycol components of polyester B.

Glycol components other than the compound of formula (II-b) contained in polyester B include ethylene glycol, diethylene gelcol, etc., and ethylene glycol is usually used.

Polyesters A and B can each be prepared by a method generally employed for producing polyesters. For example, a direct esterification method in which a dicarboxylic acid component and a glycol component are directly reacted to perform polycondensation; or a transesterification method in which a dimethyl ester of the dicarboxylic acid component and a glycol component are reacted to perform transesterification. be done. Preparation may be carried out either batchwise or continuously.

The above polyester A and polyester B are.

It is contained in the resin composition forming the thermal adhesive layer of the laminated film of the present invention in a weight ratio of 80:20 to 50:50.

If polyester A is excessive, the sealed portion will have tough properties when the obtained laminated film is thermally bonded.
Ease of opening is reduced. If polyester B is in excess, the adhesiveness of the thermal adhesive layer increases, and when the bags are processed and stacked, adhesion (blocking) of the thermal adhesive layers to each other tends to occur.

In order to form a thermal adhesive layer made of such a resin composition on a base film, polyesters A and B1 and, if necessary, other polyester resins are mixed. The mixing method is not particularly limited, but examples include the following method: (i) Dissolving polyesters A and B in appropriate solvents and mixing the resulting solutions, or mixing polyesters A and B with chips ( (2) Melt and mix polyesters A and B in an extruder, extrude them into strands or sheets, cut them into chips, and dissolve the mixture in a suitable solvent. (3) When polyesters A and B are synthesized, other polyesters are added (e.g., in the form of chips) to a polymerization vessel containing the melt, mixed, and extruded into a strand or sheet. Cut and shape the bottom into chips. Various additives are further added to the polyester resin mixture containing polyesters A and B as main components, if necessary. Examples of additives include lubricants, antistatic agents, antifogging agents, gas barrier agents, stabilizers, colorants, plasticizers, blocking agents, and conductivity imparting agents.

The polyester resin laminate film of the present invention includes, for example,
It is prepared as follows.

(1) A solution or dispersion containing the above resin composition for forming a thermal adhesive layer is applied to the surface of a monoaxially or biaxially stretched base film, and then dried. If necessary, this film is further uniaxially or biaxially stretched.

The solid content contained in the solution or dispersion of the resin composition is 5
~20% is suitable, and the solvents used include, for example, chloroform, ethylene dichloride, methyl ethyl ketone, toluene, acetic acid esters, or mixtures thereof.

(2) A resin such as polyethylene terephthalate (PET) for forming the base film and a resin composition for forming the thermal adhesive layer are charged into separate extrusion barrels, and co-extruded from one die. Prepare a laminated film. If necessary, this laminated film is uniaxially or biaxially stretched.

(3) Melt-extrude and laminate a resin composition for forming a thermal adhesive layer on a monoaxially or biaxially stretched base film, and further perform axial or biaxial stretching if necessary. These methods Among these, the coextrusion method is the most advantageous in terms of cost.

The final thickness of the base film of the laminated film prepared by such a method is usually 10 to 5 ooμm, and particularly when used as a packaging film, the final thickness is 5 to 3 ooμm.
0 μm is suitable. The thickness of the resin composition of the obtained laminated film varies depending on the use of the film, but is usually 1.
~50 μm, preferably 2 to 15 μm.

The laminated film of the present invention is used for applications such as thermal adhesive packaging. For example, two laminated films are laminated so that the thermal adhesive layer and the base film are in close contact with each other, or the thermal adhesive layers are in close contact with each other, and then compressed using a heating bar from above and below. Thermal bonding is performed by. Since the thermal adhesive layer of the laminated film is composed of a specific composition as described above, thermal bonding is easily performed. Furthermore, the adhesiveness between the thermal adhesive layer and the base film is also good, and the adhesive portion has tough properties.

Therefore, when this adhesive part is to be peeled off again, it is possible to do so by simply applying a moderate amount of force, and the stress may be concentrated in a specific part and the base film may break midway.
To prevent the base film from being torn in an undesirable direction and being damaged when the seal portion is not sufficiently peeled off. A laminated film in which the base film is uniaxially or biaxially stretched is particularly suitable for applications such as packaging that utilizes thermal adhesive properties. Since both the base film and the thermal adhesive layer of the laminated film of the present invention are mainly made of polyester, scraps, defective products, or used laminated films generated in the manufacturing process of the laminated film are collected. It is possible to use it again as a raw material (especially as a raw material for a base film). On the other hand, a laminated film in which a heat adhesive layer made of polyethylene is formed on a polyester base film cannot be recycled in this manner. In addition to being used as a heat-adhesive film, the laminated film of the present invention can also be used as a gas barrier film by vapor-depositing metals, etc.; it can also be used as a film for printing, printing, dyeing, etc. It can also be used by laminating it with other films.

(Example) Examples of the present invention will be described below.

Jitsugo” mouth.

(A) Preparation of laminated film: Polyester chips having the compositions shown in the table below were prepared as polyesters A and B, respectively. (In the table below, the composition of polyester is shown in mol%, and the blending ratio of polyesters A and B is shown in weight ratio.

+, V, indicate the intrinsic viscosity. TPA is terephthalic acid, E
G is ethylene glycol, NPC is neopentyl glycol, DE! ' is 2,2-diethyl-1,3-propanediol, IPA is isophthalic acid, AA is adipine L
AZ stands for azelaic acid, BD stands for 1,4-butanediol, and HD stands for 1,6-butanediol). 2
The extrusion barrels of the machine are connected to one T-shaped die, one of which is charged with the above polyesters A and B in the ratio shown in the table below, and the other barrel is charged with polyethylene terephthalate (PET; 1.'/, = 0.62).

Both barrels were heated to 280°C to melt the resin, and the laminated film was extruded from a T-shaped die. This laminated film
It was wound around a rotating cooling roll (20° C.) to cool and solidify. In this film, the base film layer (PE
The thickness of the T layer) is 160 μm, and! The thickness of the attached layer (layer containing polyesters A and B) was 30 μl. This film was heated to 85°C and passed between two sets of nip rolls with different rotational speeds in the direction of film travel.
Stretched twice. The obtained uniaxially stretched film was fed into a stenter one-type transverse stretching machine, and was stretched 3.6 times in the direction perpendicular to the above while heating to 95°C. The film was then treated with hot air at 210° C. while relaxing and wound up. In this process, the film is attached to the roll! No phenomenon of curling or curling was observed.

(B) Evaluation of laminated film (1) Measurement of heat seal energy = Two laminated films obtained in section (A) are stacked so that their thermal adhesive layers are in contact with each other, and 20 (1) Then, thermal bonding was performed at a temperature of 100° C. over a length of 10 m in the longitudinal direction. This film was cut into strips with a width of 15 cm to obtain test pieces, which were left in an atmosphere of 20° C. and 165% R11 for 24 hours. One end of one film of this test piece was fixed, and the opposite end of the other film was pulled in the length direction of the film at a speed of 200 m/min using Tensilon (manufactured by Toyo Baldwin).

This resulted in complete separation of the thermally bonded portion or rupture of the film.

At this time, the force applied to Tensilon against the peeling length of the film was graphed, the area under the curve was determined, and this was taken as the sealing energy (g-cm/15o).

(2) Heat sealing strength 2 In measuring the above heat sealing energy, the force applied to Tensilon at the time of complete peeling of the thermally bonded portion or film breakage was measured. Measure 5 times and calculate the average value as heat seal strength (g/1
5m).

(3) Unsealability: The two laminated films obtained in section (A) were stacked so that the thermally adhesive layers were in contact with each other, and thermally bonded for 2 seconds at a temperature of 100'C and a pressure of 2kg weight/c12. .

This film was peeled off by hand, and the state of the film at this time was evaluated.

○: Completely peeled off.

△: The base film was broken near the end point of peeling.

×: The base film was broken immediately after the start of peeling.

(4> Blocking resistance: Layer the two laminated films obtained in section (A) so that their thermal adhesive layers are in contact with each other,
A pressure of 0.07 kg weight/cI112 was applied to this in an atmosphere of 50° C. and 50% RH, and the state of the film was evaluated after being left for 24 hours.

○: No attached part.

Δ: One part is attached.

×: Most of the particles are attached.

(5) Operational stability: Changes in the state of the film obtained when the film was continuously prepared were evaluated.

○: Almost no change in film thickness after 20 hours of continuous operation.

Δ: After 10 hours of continuous operation, a large change occurs in the thickness of the film.

X: A large change occurs in the film thickness before 10 hours of continuous operation.

The evaluation results of (1) to (5) above are shown in the table below. Example 2
The results of Comparative Examples 1 to 6 and Comparative Examples 1 to 5 are also shown in the table below.

Actual length 1 pull-up] - A polyester resin laminate film was prepared in the same manner as in Example 1, except that the composition and blending ratio of polyesters A and B were changed as shown in the table below.

A polyester resin laminate film was prepared in the same manner as in Example 1 except that the blending ratio of the main polyesters A and B was changed as shown in the table below. The laminated film obtained in Comparative Example 1 had low heat sealing energy and lacked unsealability.

The laminated films obtained in Comparative Examples 2 and 3 lacked blocking resistance and operational stability.

A polyester resin laminate film was prepared in the same manner as in Example 1, except that the composition and blending ratio of the Summer Salmon Soil Polyesters A and B were changed as shown in the table below. The laminated films obtained in Comparative Examples 4 and 5 lacked unsealability, and the film of Comparative Example 6 lacked operational stability.

(Margins below) From the table, it can be seen that the laminated film of the present invention retains high sealing energy and has high sealing strength when thermally bonded.
It also has excellent opening properties. Furthermore, blocking between the thermal adhesive layers is less likely to occur, and even when processed into a bag shape and stacked, problems such as films adhering to each other do not occur. On the other hand, the laminated films of Comparative Examples 1 and 2, in which the thermal adhesive layer is composed of only one of polyesters A and B, have low sealing strength and lack unsealability or blocking resistance. As in Comparative Example 3, when the blending ratio of polyesters A and B deviates from the claimed range, there is a problem in blocking resistance.

As in Comparative Examples 4 to 6, when the composition of polyester B deviates from the claimed range, unsealability or operational stability is lacking.

(Effects of the Invention) According to the present invention, a polyester resin laminate film having excellent thermal adhesiveness can be obtained. Since this film has a heat-adhesive layer mainly composed of polyesters A and B containing specific components, it has excellent unsealability and blocking resistance, and the heat-adhesive portion has tough properties. Such laminated films are suitably used for various purposes such as packaging films and gas barrier films.

that's all

Claims (1)

[Claims] 1. A base film made of a polyester resin, and a thermal adhesive layer made of a resin composition containing polyester A and polyester B as main components, provided on at least one side of the base film. A polyester-based resin laminate film, wherein the polyester A contains at least one glycol component represented by the following formula (I), and the polyester B comprises:
It contains at least one dicarboxylic acid component represented by the following formula (II-a) and at least one glycol component represented by the following formula (II-b), and the polyester A and the polyester B have a ratio of 80:20 to 50:50. Polyester resin laminated film contained in the composition by weight ratio: ▲Mathematical formulas, chemical formulas, tables, etc.▼(I) Here, R_1 and R_2 are hydrogen and carbon atoms from 1 to
6 alkyl groups, at least one of which is an alkyl group having 1 to 6 carbon atoms, n and m are integers of 1 to 6, and HOOC-(CH_2)p-COOH(II-a) where , p is an integer of 4 to 10, HO-(CH_2)q-OH(II-b) where q is an integer of 4 to 20.