JP2920398B2 - Bags for packaging skim milk powder - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a bag for skim milk packaging, in which an inner bag made of a composite synthetic resin film is provided inside an outer bag made of kraft paper, The present invention relates to a bag that can be obtained without any quality problem by a bag making machine for a bag for defatted milk powder that is heat-sealed or melted from paper.

(Conventional technology and its problems) As the above-mentioned bag for defatted milk powder packaging, one having a structure in which an inner bag made of a single-layer film made of low-density polyethylene resin is arranged inside an outer bag usually made of kraft paper is used. Have been.

Further, in a bag making machine for manufacturing a bag having such a configuration, a cut product obtained by cutting the outer bag into which the inner bag has been inserted into a regular size is usually used, and the outer bag is heated from the outside and heated at the bottom of the inner bag. After sealing and then fusing only the inner bag, the bag end is machined from the outside to make the bag.

However, when the bag is made using the inner bag and the outer bag made of the single-layer film made of the low-density polyethylene resin,
A part of the inner bag and the kraft paper of the outer bag are heat-sealed by heat sealing, and when filling with skim milk powder, the part may be peeled off and pinholes may occur, and the inner bag has gas barrier properties The powdered skim milk powder adsorbed other odorous components due to poor quality, and there was a problem in quality.

(Means for Solving the Problems) The present invention has found a bag for defatted milk powder packaging which is less likely to generate pinholes and has excellent gas barrier properties.
The gist of the invention is that in a bag for skim milk powder packaging in which an inner bag made of a composite synthetic resin film is provided inside an outer bag made of kraft paper, the inner bag is an ethylene-vinyl acetate copolymer soap having an intermediate layer. The present invention provides a bag for defatted milk powder packaging, comprising a composite film having a linear low density polyethylene resin layer having a melt flow rate (MFR) in the range of 0.5 to 2.0 on both sides of the compound.

Although the bag body of the present invention has a double bag structure in which an inner bag is arranged inside an outer bag, the kraft paper used for the outer bag is preferably made of ordinary kraft paper having a thickness of 2 to 3 times. A composite film having a specific layer configuration can be used as the inner bag.

For the middle layer of the composite film used for the inner bag, a saponified ethylene-vinyl acetate copolymer (hereinafter referred to as "EVOH") is used to impart gas barrier properties.
When the ethylene content is in the range of 35 to 45 mol%, the degree of saponification is
Those having a mole percentage of 95 mol% or more and a thickness of about 3 to 10 μm can be suitably used.

Further, it is necessary to arrange a linear low-density polyethylene resin (hereinafter, referred to as “LLDPE”) in the outer layer and the inner layer (sealing material layer) of the intermediate layer. By sandwiching the EVOH layer with the polyolefin layer, the occurrence of pinholes in the rigid EVOH layer can be reduced.

As the LLDPE, it is necessary to use those having a melt flow rate (MFR, JISK7210) of 0.5 to 2.0 for both the outer layer and the inner layer. If the outer layer has an MFR of less than 0.5, the tensile strength is reduced and the sealing strength is inferior. If the outer layer has an MFR of more than 2.0, the kraft paper and the film are fused by heat sealing and pinholes are liable to occur. Also, for the inner layer (seal material layer), it is necessary to use LLDPE having an MFR in the range of 0.5 to 2.0, as described above. If it is less than 0.5, the tensile strength is reduced and the sealing strength is inferior. Then, the heat-sealing makes the fused portion non-uniform (a non-uniform seal portion more than the seal width is generated), and pinholes are easily generated. The thickness of the inner layer is preferably in the range of about 50 to 100 μm.

Various adhesive resins such as carboxylic acid-modified polyolefin can be interposed between the above-mentioned resin layers in order to improve the adhesiveness between the layers.

Furthermore, the composite film for an inner bag of the present invention can be produced by a usual production method, but a method of laminating and forming a film by a co-extrusion method is general.

 Hereinafter, the present invention will be described with reference to examples.

(Examples) Using an outer bag and an inner bag of each configuration described later, a bag for defatted milk powder packaging was obtained by continuous heat sealing, fusing, and sewing at the end with a bag making machine.

Example 1 Outer bag; Kraft paper triple layer Inner bag; Outer layer LLDPE (15 μm, MFR = 1.0) / adhesive resin 5 μm /
Intermediate layer, EVOH 5μm / adhesive resin 5μm / inner layer LLDPE (65μm
m, MFR / 1.0) The composite film having the above configuration is formed into a film by a co-extrusion method.
I got an inner bag. Using the outer bag and the inner bag, a bag was obtained by the above-described method using a bag making machine.

As a result, no fusion between the film and the kraft paper due to heat sealing was observed, and as a result, no pinholes were generated due to the filling of the skim milk powder, and there was no problem of odor.

Example 2 A bag was obtained by the above-described method using a composite film having the same contents as in Example 1 except that the MFR of the LLDPE used was 0.6. As a result of performing the same evaluation as in Example 1, the result was the same as that of Example 1, and there was no problem.

Comparative Example 1 A bag was obtained by the same method using a composite film having the same contents as in Example 1 except that the MFR of the LLDPE used was 2.2. As a result, there was a non-uniformly fused portion in the width of the seal portion due to heat sealing, and pinholes were generated by filling.

Comparative Example 2 A bag was obtained in the same manner as in Example 1, except that LDPE (MFR0.8) was used instead of the outer and inner LLDPEs. As a result, the sealing strength was weak, and pinholes were generated by filling.

Comparative Example 3 Same as Example 1 except that 6 nylon was used instead of EVOH. High temperature was required during fusing, and the kraft paper burned. Further, the gas barrier properties of the bag were inferior and there was a problem of odor.

(Effect of the Invention) As described above, according to the bag for skim milk powder packaging of the present invention, there is an advantage that pinholes do not occur due to filling with skim milk powder, and the gas barrier is excellent and there is no odor problem.

Claims (1)

(57) [Claims] 1. A bag for packaging skim milk powder in which an inner bag made of a composite synthetic resin film is provided inside an outer bag made of kraft paper, wherein the inner bag is made of a saponified ethylene-vinyl acetate copolymer in an intermediate layer. 0.5 melt flow rate (MFR) on both sides
A bag for packaging skim milk powder, comprising a composite film having a linear low-density polyethylene resin layer in the range of 2.0 to 2.0.