JPH0326528A - Production of laminate - Google Patents

Abstract

PURPOSE:To enable containers with barrier properties to be produced on a multiitem small-lot basis through simple steps and with little loss, by a method wherein at least two polypropylene resin sheets having respectively specified melt indices and thicknesses and preliminarily coated with a polyvinylidene chloride resin in a specified thickness are welded to each other through the polyvinylidene resin layers thereof. CONSTITUTION:At least two sheets of polypropylene resins 1, 1' preliminarily coated respectively with polyvinylidene chloride resins 2, 2' in thicknesses of 1 to 30mum are welded to each other through the polyvinylidene resin layers thereof. The polyvinylidene resins 1, 1' have respective melt indices of 0.005 to 80g/10min and thicknesses of 10 to 300mum. Thus, a polyvinylidene resin laminate having barrier properties and suitable for multiitem small-lot production can be obtained without using a polyvinylidene resin multilayer film or sheet forming machine, and with little loss at startup and little loss on specification changes.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for manufacturing a laminate. More specifically, the present invention relates to a method for producing a laminate, which is a barrier layer, and includes a polyvinylidene chloride resin layer and a propylene resin layer interposed therebetween, by thermal fusion.

[Conventional technology]

Conventionally, barrier containers using polyvinylidene chloride resin as a barrier layer have been made using special multilayer films for polyvinylidene chloride resin and sheet molding machines (forming machines with very special plating and flow path shapes). It has been common practice to manufacture a vinylidene chloride-based resin multilayer film or sheet, and then to manufacture a barrier container by thermoforming the multilayer film or sheet.

[Problem to be solved by the invention]

When manufacturing barrier containers using the method described above, not only is it necessary to use a special multilayer film or sheet molding machine as described above, but the molding technology is also much more difficult than in the case of polyolefin resins. Moreover, the start-up loss required for stable production of multilayer films and sheets is 5 to 10 times that of polypropylene resins, for example. Further, depending on the shape of the container, although it is not necessary to change the thickness of the sheet, it is necessary to change the thickness of each layer of the multilayer film or sheet to some extent due to economic reasons. In that case, a large amount of loss occurs due to the change in thickness.

In other words, when using a commonly used multilayer film or sheet forming machine, it is advantageous when the lot is very large due to the nature of the machine, but it is not possible to use a manufacturing method that is completely compatible with the recent manufacturing of a wide variety of lofts. I couldn't say yes.

From the above, the present invention does not have these drawbacks, and does not require the use of a multilayer film or sheet molding machine for polyvinylidene chloride resin, and is more suitable for high-mix, low-volume production than conventional manufacturing methods. The object of the present invention is to provide a polyvinylidene chloride resin barrier laminate.

[Means and effects for solving the problems] According to the present invention, these problems can be solved in advance by using
This is a method for producing a laminate by thermally fusing the polyvinylidene chloride resins of at least two laminates of polypropylene resin coated with polyvinylidene chloride resin, each having a melt index ( According to JIS K7210, condition 1
4, the iill J constant (hereinafter referred to as "M I (1) J") is 0.005 to 80 g/10 min, and the thickness of the polypropylene resin layer is 10 to 300 g/10 min. This problem can be solved by a method for manufacturing a laminate.The present invention will be specifically described below.

(^) Polypropylene resin The polypropylene resin used in the present invention is a propylene homopolymer or brobylene containing at least 70 iR.
Examples include random or block copolymers with ethylene or other α-olefins containing ffi%, or random or block copolymers with α-olefins; You can. M 1 (
1) is 0.005 to 80 g/10 minutes, and 0.01 to
70g/10min is preferable, especially 0.01~
60 g/10 min polypropylene resin is preferred.

If a polypropylene resin with an M I (1) of less than 0.005 g/10 minutes is used, the molding processability to obtain a laminated long product will be poor, and a good container will not be obtained. If such a resin is used, the impact resistance of the container will be weak, and when molded into a container, it will not only be unsuitable for practical use, but also have poor moldability.

In the present invention, the polypropylene resin alone may be used, but in order to improve the rigidity of the polypropylene resin, an inorganic filler described below may be added.

The inorganic filler of the present invention is generally widely used in the fields of synthetic resins and rubbers.

These inorganic fillers are preferably inorganic compounds that do not react with oxygen and water, and that do not decompose during crosstalk or molding.

Examples of the inorganic filler include oxides of metals such as aluminum, copper, iron, lead, nickel, magnesium, calcium, barium, zinc, zirconium, molybdenum, silicon, antimony, and titanium, and hydrates (hydroxides) thereof; It is broadly classified into compounds such as sulfates, carbonates, and silicates, their double salts, and mixtures thereof. Representative examples of the inorganic filler are described in Japanese Patent Application No. 124481/1981.

Among these inorganic fillers, those in powder form have a diameter of 3
0 m or less (suitably 10 m or less) is preferable. In addition, in the case of fibrous materials, the diameter is 1 to 500 μs (preferably 1 μs).
~330μs), and the length is 0.1~8.0+u+(
A preferable range is 0.1 to 5.0 m+i).

Furthermore, for flat plate-shaped ones, it is less than 30μs (preferably lOm
The following) are preferred. Among these inorganic fillers,
Particularly suitable are plate-like (flake-like) ones and powder-like ones.

The composition ratio (content ratio) of the inorganic filler in the inorganic filler-containing polypropylene resin is at most 70% by weight, preferably 1.0 to 65% by weight, particularly 1.
0 to 60% by weight is preferred. The ratio of the inorganic filler in the inorganic filler-containing polypropylene resin is 1.0.
If the amount is less than % by weight, the rigidity of the resulting container cannot be improved satisfactorily. And the combustion calorific value during incineration is 7
000kcal/kg or more and does not become an easily incinerated resin. On the other hand, if it exceeds 70% by weight, the impact resistance of the resulting container will be significantly reduced, resulting in a container that is not suitable for practical use.

Further, a polyethylene resin described below may be blended with the polypropylene resin in order to improve impact resistance at low temperatures. At this time, the proportion of polyethylene resin in the total amount of polypropylene resin and polyethylene resin is usually at most 50% by weight (preferably 30% by weight).
below).

Examples of the polyethylene resin include single ethylene polymers and copolymers of ethylene and α-olefins having at most 12 carbon atoms (for example, propylene, butene-1, 4-methylpentene-1, octene-1). .

The copolymerization ratio of α-olefin in the copolymer of ethylene and α-olefin is usually at most 15% by weight;
It is preferably 2% by weight or less, particularly preferably 10% by weight or less. The density of the polyethylene resin is generally 0.9
00 ~ 0.965 [/cd, 0.905 ~
0.960 g/cd is preferred, especially 0.910
~0.955 g/cJ is suitable. Furthermore, the melt index (measured under conditions 4 according to JIS K-7210, hereinafter referred to as rM I (2) J) is usually 0.01 to 80 g/m for the same reason as the polypropylene resin.
io minutes, preferably 0.02 to 60 g/lO minutes,
Particularly suitable is 0.05 to 50 g/10 minutes.

The polyethylene resin may be a low-density polyethylene produced by a so-called high-pressure method, or a linear low-density to high-density polyethylene produced by a so-called Phillips catalyst or Ziegler catalyst.

(B) Polyvinylidene chloride resin The polyvinylidene chloride resin used in the present invention includes vinylidene chloride homopolymers and copolymers of vinylidene chloride and other comonomers. Multi-component copolymers of vinylidene chloride and other comonomers as well as third and/or fourth components can also be used.

Other comonomers include acrylic esters, methacrylic esters, acrylonitrile and vinyl chloride. In addition, as the third component and the fourth component,
Examples include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and unsaturated dicarboxylic acids such as maleic acid.

In the case of the above copolymers and multicomponent copolymers,
In both cases, the copolymerization ratio of vinylidene chloride is at least 60
mol%, preferably 65 mol% or more, especially 7
The content is preferably 0 mol% or more. When the copolymerization ratio of vinylidene chloride is less than 60 mol %, crystallization of the coating film hardly occurs, and its contribution to the barrier properties against carbon dioxide gas and water vapor is small. However, in the case of a powder type, if the copolymerization ratio of vinylidene chloride is 94 mol% or more, there is a limit to the solvent in which it can be dissolved, and in the case of an aqueous dispersion, if the copolymerization ratio of vinylidene chloride exceeds 92 mol%. , it tends to gel and lacks stability. Whether it is a vinylidene chloride copolymer or a multi-component copolymer, the coating on the base film may be water-based, but the manufactured container must be subjected to high retort treatment (125°C, 30 minutes). ,
When using it as a plastic container, in order to prevent the barrier properties from deteriorating after retorting, vinylidene chloride copolymers and multi-component copolymers should be mixed with organic solvents such as methyl ethyl ketone, toluene, tetrahydrofuran, methyl isobutyl ketone, and acetone. It is better to carry out with a solution dissolved in a solvent.

In addition, a solution containing 15% by weight dissolved in methyl ethyl ketone was measured using a Pruckfield viscometer (Brookfield viscometer) at a temperature of 25°C.
ookfield rotational visco
It is preferable that the viscosity is 50 to 600 cetimboaz as measured by mcntcr). If the viscosity is less than 50 centiboads, cracks are likely to occur during container molding, and the barrier properties are somewhat poor. On the other hand, if it exceeds 600 centiboads, it becomes difficult to coat.

Furthermore, when used as an aqueous dispersion, it can be obtained by dispersing the copolymer or multicomponent copolymer using a surfactant or other additives in addition to the surfactant, as is generally done.

(C) Coating method As a method for coating polyvinylidene chloride resin on polypropylene resin, a dip coater, Meyer bar coater, Clavia coater, roll coater, air knife coater, etc. are used depending on the purpose. be able to.

Since polypropylene resin does not have a polar group, its adhesion with polyvinylidene chloride resin is poor. For this purpose, it is preferable to treat the surface of the elongated object of the polypropylene resin in advance as described below. Examples of the treatment method include a corona discharge treatment method, a high frequency treatment method, a flame treatment method, and a chromic acid solution treatment method.

(D) Film or sheet and production thereof The polypropylene resin or the composition comprising the polypropylene resin, polyethylene resin and/or inorganic filler is processed into a "film" by the T-die method commonly practiced in the field of olefin resins. Or sheet”
[Hereafter referred to as "thin material"].

Further, the polypropylene resin thin material coated with the polyvinylidene chloride resin of the present invention can be produced by coating the polypropylene resin thin material with the polyvinylidene chloride resin as described above.

When manufacturing thin-walled products, the shapeability is poor at low temperatures. On the other hand, at high temperatures, the resin used may undergo thermal decomposition (thermal deterioration). From the above, generally 180
What is necessary is just to carry out at -240 degreeC (preferably 190-230 degreeC).

This is a polypropylene resin layer coated with the polyvinylidene chloride resin obtained in this way, and 2 is a polyvinylidene chloride resin layer.

The thickness of the polypropylene resin to be coated is lO
-300tln, preferably 20-200IEn, particularly preferably 30-100IEn. If the thickness is less than 10 mm, the thin material will stretch during coating and thermoforming, which is undesirable. On the other hand, if it exceeds 300, the coating properties of the polyvinylidene chloride resin will be poor and the cost will be high, which is not preferable.

Furthermore, the thickness of the polyvinylidene chloride resin layer is 1.0~
30μ, preferably 1.0 to 28μ, especially 1
．． 2-25- is suitable. If the thickness of the polyvinylidene chloride resin layer is less than 1.0 mm, it is not preferable because not only the barrier properties are low but also cracks are likely to occur in the barrier layer. On the other hand, if the length exceeds 30m, not only will it be necessary to turn the court many times, but the cost will also increase.
Moreover, the adhesive strength also decreases, and there is a risk of delamination during retort processing, for example.

(E) Laminated product and its production The polyvinylidene chloride resin layers of at least two thin polypropylene resin coated with polyvinylidene chloride resin are thermally fused to each other. Generally, a thermal lamination device using heated rolls may be used for this thermal fusion. In this way, a laminate whose partially enlarged sectional view is shown in FIG. 1 can be obtained.

Furthermore, as shown in FIGS. 3 and 4, respectively, it is possible to manufacture a laminate in which a plurality of thin materials are laminated, the partially enlarged sectional view of which is shown in FIG. 2. Can be done. In FIGS. 3 and 4, 1.1' and 1' are polypropylene resin layers, and 2.2
', 2'' and 2' are all polyvinylidene chloride resin layers.

There are various methods for manufacturing the laminate whose partially enlarged sectional view is shown in Fig. 3, but as an economical method, the first method is to produce a partially enlarged sectional view as shown in the first example. The laminates shown are laminated by thermal lamination, one of the polypropylene resin layers of the resulting laminate is coated with polyvinylidene chloride resin as described above, and this polyvinylidene chloride resin layer is coated with a first layer of polyvinylidene chloride resin. It can be manufactured by heat-sealing the polyvinylidene chloride resin layer of the laminate whose partially enlarged sectional view is shown in the figure as described above.

Furthermore, as for the manufacturing method of the laminate whose partially enlarged sectional view is shown in FIG. 4, various methods are listed as in the case of the laminate whose partially enlarged sectional view is shown in FIG. However, an economical method is to laminate the laminates shown in the partially enlarged cross-sectional view shown in FIG. It can be manufactured by laminating them using a thermal lamination method.

Another method is to further coat the polypropylene resin layer of the laminate whose partially enlarged cross-sectional view is shown in FIG. 2 with polyvinylidene chloride resin as described above, and to A method of thermally fusing either layer and the polyvinylidene chloride resin layer of the laminate whose partially enlarged sectional view is shown in FIG. The polyvinylidene chloride resin layer may also be manufactured by heat-sealing the polyvinylidene chloride resin layer of the laminate whose partially enlarged sectional view is shown in FIG. 2 as described above.

[Examples and comparative examples]

Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the Examples and Comparative Examples, the oxygen permeability was measured using an oxygen permeation amount measuring device (manufactured by Modern Control Co., Ltd., model O X T R A N 10/50) at an oxygen pressure of 1 atm and a temperature of 20°C. and relative humidity of 90%
Measured under the following conditions.

Example 1 As a thin material of polypropylene resin used to coat polyvinylidene chloride resin described later, the copolymerization ratio of ethylene was 4.8% by weight, and M 1 (1) was 3.5 g/
10 minutes propylene-ethylene random copolymer 1
00 parts by weight and M I (2) of 7.5 g/lO, a density of 0.925 g/ci, and a copolymerization ratio of butene-1 of 7.3% by weight. A film (70 m thick) prepared by mixing 20 parts by weight of Ten-1 copolymer was used.

In addition, as the polyvinylidene chloride resin for coating, vinylidene chloride is 93 mol, the copolymerization ratio of methacrylic acid ester is 5.5 mol%, and the copolymerization ratio of acrylonitrile is 1.5 mol%. A solution was used in which 20 parts by weight of a certain vinylidene chloride-methacrylic acid-acrylonitrile terpolymer was dissolved in a mixed solution consisting of 40 parts by weight of toluene and 40 parts by weight of tetrahydrofuran.

The surface of the polypropylene resin film was subjected to corona treatment, and an undercoat agent (manufactured by Nippon Polyurethane Co., Ltd., trade name Coronate L) was applied to the treated film with a water contact angle of 75 degrees using a gravure coater. The coating was applied in an amount of 0.2 glrd. This coated surface was coated with the above solution using a coater using a Meyer bar method at a coating amount of Log/Po, dried at a temperature of 105°C for 100 seconds, and then formed into a laminate [hereinafter referred to as "laminate"].
A) was produced.

The thus obtained laminate (A) was made with two polyvinylidene chloride resin layers on the inside, using a heat laminator (manufactured by Okajima Kikai Kogyo Co., Ltd.) as shown in the cross-sectional view in Figure 1. Each polyvinylidene chloride resin was heated and laminated so that the surface temperature reached 160°C. The adhesive strength of each laminate (A) of the obtained laminate was 211 peeling strength at 90 degrees of 1450 g/15 mm. Further, the oxygen permeation amount was 0.8 cc/r+f·atm·day.

The obtained laminate and M I (+) are 0.5 g/1
Using a 0 minute ethylene-propylene block copolymer (copolymerization ratio of ethylene: 18% by weight), a T-die sheet forming device with a laminating device (manufactured by Toshiba Machine Co., Ltd., screw diameter 65 mm, die width 200 om) was used. and set the resin temperature to 2.
The temperature was adjusted to 30° C., and the sheet was shaped to have a thickness of 1.5 mm after lamination. The amount of oxygen permeation through the bonded thread is 0.
9cc/rr?・Atmospheric pressure/day.

The obtained laminated sheet was molded to a diameter of 81.2 mm using a vacuum forming machine (manufactured by Asano Research Institute, model F L V 441).
am, a container with a depth of 50161% and a capacity of 170 cc was manufactured. 5% of the total content in the container thus obtained
Fill with water so that the head space is 2, and the thickness is 2.
A lid made of propylene polymer with a thickness of 60 mm on both sides with aluminum foil of Tm interposed between the lids was heated at a temperature of 200°C.
Sealing was performed for 3 seconds at a pressure of 2.5 kg/c- to produce a container filled with water. The obtained container was placed in a retort pot (manufactured by Daiwa Can Co., Ltd., model KHR-
W-101-M) at a temperature of 125°C.
Retort processing was performed for 1 minute. After that, the measured temperature is 20
℃, and the relative humidity inside the container was 90%, and the relative humidity outside the container was 60%. The amount of oxygen permeation was 0.02 cc/atm/day.

Example 2 Using two laminates whose partially enlarged cross-sectional view is shown in FIG. They were heated and laminated to achieve the desired results. The oxygen permeability of the obtained laminate; gJm is 0.4cc/rr? It was ●atmospheric pressure● days. A laminate (lamination sheet) was produced in the same manner as in Example 1, except that the thus obtained laminate whose partially enlarged sectional view is shown in FIG. 4 was used. The oxygen permeation rate of the obtained laminated sheet was 0.4 cc/ryf/atmospheric pressure/mouth.

Using the obtained laminated sheet, a container was manufactured in the same manner as in Example 1, and the amount of oxygen permeation was measured under the same conditions as in Example 1. The oxygen permeation rate of the obtained container was 0.01 cc/atm/day.

Example 3 One side of the laminate used in Example 1, whose partially enlarged sectional view is shown in FIG. 1, was further coated with polyvinylidene chloride resin in the same manner as in Example 1. In this way, the oxygen permeation rate of the polyvinylidene chloride resin laminate is 0.4cc/rr?・Atmospheric pressure/day. A polyvinylidene chloride resin layer of the laminate whose partially enlarged sectional view is shown in FIG. 2 was heated and laminated in the same manner as in Example 1 to the polyvinylidene chloride resin layer of the obtained laminate.

A partially enlarged sectional view of the obtained laminate (lamination sheet) is shown in FIG. The adhesive strength of this laminated sheet was measured in the same manner as in Example 1 and was 1.300 g/15+am, and the oxygen permeation amount was 0.48 cc/rd·atm·day. A container was manufactured from this laminated sheet in the same manner as in Example 1, and the amount of oxygen permeation was measured. The oxygen permeation rate of this container is 0.00
It was 8cc/piece/atmosphere/day.

The results of Examples 1 and 2 show that the oxygen permeability of the container can be controlled by changing the number of laminates of the present invention.

〔Effect of the invention〕

The laminate of the present invention is characterized in that the polyvinylidene resins of at least two laminates of polypropylene resin coated with polyvinylidene chloride resin are thermally fused to each other. It can be used by being molded into a plastic container, and the barrier properties can be controlled by changing the number of heat-sealed sheets.

It is believed that the laminate of the present invention can be shaped into a container and used in a wide variety of ways. Typical uses are shown below.

(1) Various processed seasoning food containers (2) Various liquid food containers (3) Multilayer food containers (4) Various food vouchers

[Brief explanation of drawings]

FIG. 2 is a partially enlarged sectional view of a polypropylene resin layer coated with polyvinylidene chloride resin used in manufacturing the laminate of the present invention. Also, Figure 1,
FIGS. 3 and 4 are partially enlarged cross-sectional views of typical laminates of the present invention.

Claims (1)

[Claims] A method for producing a laminate in which the polyvinylidene chloride resin layers of at least two laminates of polypropylene resin coated with a polyvinylidene chloride resin having a thickness of 1 to 30 μm are thermally bonded to each other, The melt index of each polypropylene resin is 0.0
05 to 80 g/10 minutes, and the thickness of each polypropylene resin layer is 10 to 300 μm.