JPS58186698A - Base paper for lamination - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a forming laminated base paper and a laminate of the base paper with a thermoplastic resin.

The purpose of the present invention is to provide a liquid base paper for laminate that can withstand heating for thawing and cooking the contents, food, etc. while still in the four containers when molded into six containers. It's about doing.

Aluminum foil, for example, has traditionally been considered for this purpose.Although it is moisture-proof, soft and moldable, it reflects heat and has poor thermal efficiency.As it has good thermal conductivity, the surface gets hot after heating, making it difficult to handle. It is inconvenient.

In addition, there are disadvantages such as food being easily cooled after cooking, being too flexible and not stable in shape, being unusable due to heat generation in the T-4 microwave, and lack of water retention, so overall it is not satisfactory. do not have. Plate made only of paper is not waterproof enough, and even if you put the contents in it, it will boil over.

The plate deforms due to the absorption of meat juices, etc., and the contents cannot withstand subsequent freezing and reheating.

In order to prevent the contents from affecting the paper, it is presumed that it is best to laminate a resin film such as polyolefin or polyethylene terephthalate onto the paper, but it is generally used as a single paper for packaging, such as in ordinary boxes. When white paperboard is used, it is made by combining sheets and consists of many paper layers, so it is relatively weak in terms of strength, and when molding, it is particularly difficult to draw deep or fold at an acute angle. This method causes cracking of the paper and peeling of the paper layer, so its practical use is limited.

The moisture contained in the frozen inner paper layer causes the paper layer to peel during thawing. The paper swells due to moisture or the simultaneous action of moisture and heat, significantly reducing its strength, making it completely unable to withstand steaming. Moisture and heat can cause the paper to warp or bend, causing it to change shape during molding, and discoloration caused by heat is significant, so it cannot be used for purposes such as baking the contents. This causes other inconveniences and is not practical.

The present invention provides a laminate for cookable bowls and its p paper, which could not be made by using these conventional materials. That is, the base paper of the present invention is a paperboard made as a single paper layer rather than a paperboard, the inner surface is sized with a neutral sizing agent, the sizing degree is 500 seconds or more, and preferably the heel has A≧0.008B2. The base paper has a satisfactory size. (However, the above formula is expressed in seconds, and B is the number of overlays per 12 sheets of paper expressed in grams.
) This base paper ti also has a length-width ratio of elongation at tensile breakage of 0,
It is preferable that the number is 8 or more, and the neutral sizing agent preferably uses a styrene-maleic acid copolymer type.

By laminating thermoplastic polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefins, etc. on such base paper using an appropriate lamination method such as extrusion lamination, a laminate suitable for the intended use of one grape can be obtained. Complete.

The present invention will now be described in greater detail.

The base paper of the present invention is made from bleached kraft pulp without using waste paper or mechanical pulp. Although there are no particular restrictions on the material used for valves, it is easier to form the material if it contains a large amount of softwood pulp than if it is made mainly from hardwood pulp.

It is excellent in that it does not tear or break during molding, and it is easy to maintain the f degree of the paper after molding.

Other fibers such as synthetic fibers and synthetic pulp can also be blended as long as they do not impair the properties of the base paper of the present invention.

For papermaking, it is preferable to make paper by using a regular length-type 1'/) planting machine. Although the paper may be made using other paper machines, the circular mesh type #'' is not suitable because the line drawings tend to line up in the vertical direction and the aspect ratio of the strength is large, giving undesirable anisotropy to the molded product. In other words, the base paper produced by a circular mesh paper machine has significantly less elongation in the longitudinal direction than in the transverse direction, making it more likely to crack and break during drawing and forming, resulting in poor forming performance (ease of forming), poor forming performance, and moisture absorption and desorption. Af raw materials may be deformed or distorted due to this.

This is not desirable because it causes

-By combining these? : After forming the layered base paper, the paper layer naturally peels off due to the moisture contained during use, especially when thawing, or when exposed to moist heat, and the shape of the container also deteriorates.
Since H'Q is also lost, paper made by combining paper is not included in the scope of the base paper of the present invention.

The suitable basis weight for the base paper of the present invention is about 15() to 500.
f/r? If it is less than 4, there will be concerns about strength and shape retention, and if it is more than 4, it will be difficult to mold, which is undesirable. A softness of about 0.55 to 0.75 is recommended. ◇Items with a flatness are difficult to mold and have poor moisture dissipation after molding, causing the laminate layer to bulge when heated and the molded product to be easily deformed. It has drawbacks and is inconvenient. During molding, paper is subjected to rolling forces in some parts, and other parts are subjected to rolling forces.
In other words, the area around the collar is compressed. To survive both of these forces, maintaining strength and freedom from stress ['
must be maintained, and the above-mentioned dense range is most preferable.

In order to improve moldability and stability after molding, it is necessary for the paper to be isotropic. It is necessary that d is not constant.

In general, paper tends to have pulp fibers arranged vertically, so it elongates less in the longitudinal direction than in the transverse direction in a tensile test.

Particularly when a large amount of short-fed waste paper such as 4NR waste paper with low fiber strength is used, or when the paper is made using a circular screen, the gap between parts is large. If the length and width ratio of elongation at tensile break and the length and width ratio of elongation at 77 moisture tensile break are less than 73%, bK acid type breakage, moisture absorption and desorption after molding, cooling fat 1 heat, etc. Due to the strain inherent in the molding 6 due to environmental changes, the molding 6 also generates force; twisting, distortion, bending, and its utilization value is lost; therefore, it is desirable to use a force large enough to maintain the aspect ratio of elongation. This aspect ratio is 0
．． It is sufficient if it is 3 or more, and more preferably 0°45 or more. This ratio is sometimes caused by the fact that the elongation of the paper in the longitudinal direction is extremely small. This phenomenon is caused by the short fiber p
A cooking prize container made of a laminate using the base paper of the present invention containing a large amount of material must have heat resistance, hot water resistance, Ql heat resistance, heat discoloration resistance, and water resistance. Here, water resistance also means that it has a high degree of sizing, that is, it is difficult for water to penetrate (#1), or that there is little decrease in strength when wet. Normal rosin size, petroleum size, etc. have young fruits in imparting water resistance in this sense, but these can only be layered on paper fibers by using sulfuric acid band, and the effect of imparting water resistance can be exerted.

L, carbon sulfate deteriorates heat resistance. In other words, when using base paper using sulfuric acid band, the angle is 120-250°.
Heating the base paper makes it brittle and weakens, causing discoloration due to heat, which affects its strength, aesthetics, and flavor, making it unusable.

Therefore, the base paper of the present invention must be sized, but since the use of sulfuric acid is inappropriate, a neutral sizing agent is used. However, it cannot be used in terms of heat resistance and hot water resistance because it causes wax emulsion and -t. In addition, even though some rubber emulsions have the effect of increasing the strength of water-resistant paper, they are waterproof due to the surfactants they possess...which ultimately helps in water penetration when the body gets wet. It is unjust because it degrades the paper cuff. A as a neutral sizing agent
If you can find something that can prevent water penetration and maintain the composition when wet without causing the disadvantages like il Be ("
It may be I. Here, neutral size means a size that can be effectively added to paper stock without using sulfuric acid.

Such sizing agents include alkylguten dimer,
Various cation-modified neutral sizing agents 2 For example, rosin, maleated rosin, maleated xylene resin, maleated petroleum resin, etc. and reaction product of polyalkylene polyamine or co-electrode and epichlorohydrin, methylstyrene-vinylpyridine copolymer You can choose from polymers such as methyl acrylate, polyalkylene polyamine-ebichlorohydride, %, F, etc.In addition, styrene maleic acid composite resin sizing agents can also be used.This can be used as a surface sizing agent. Although it is commercially available, it has been found that in the case of the base paper of the present invention, it can be used as an internally added neutral sizing agent to achieve the purpose.

The reason for selecting these sizing agents is that they can be used for normal size 1 history without using special measures such as using an extremely large amount or using special auxiliaries, and can be used for more than 500 seconds before t1 [Formula A 0. 0
It is possible to provide a size that satisfies the requirements of 0882, provide morphological stability by preventing water penetration, and prevent deterioration of paper 77 due to water, and can be bundled into a single bundle without causing the disadvantages of thermal deterioration V and discoloration. In addition, these neutral-sized base papers sized to the above-mentioned size are laminated with thermoplastic polyester resin.

It is characterized by extremely good adhesion with polyolefin resins and does not cause peeling from the fist or swelling of the laminated resin eardrum during molding, processing, and use.

In addition to the sizing agent, there is no difference even if a conventional four-bite strength enhancer and its fixing aid are used in combination.

In order to supplement the effect of the inner size, the surface size may also be engraved.The effects brought about by the above-mentioned size applied to the base paper of the present invention and the conditions for forming the paper layer have been explained above. In addition to improving the moldability drawbacks of the prior art and preventing heat resistance, especially discoloration and deformation, it also has excellent resistance to moist heat. In other words, even if water vapor and heat are applied directly to the paper (from the outside, such as when the packaging is steamed), it will not blister or curl, and will retain its shape without contaminating the original contents. It also has the effect of being able to be heated without crumbling.

The method of coating resin on base paper of the present invention is particularly: I'
A method of bonding film and base paper without lamination.

Although an extrusion lamination method is adopted, it is preferable to use molten resin in order to take advantage of the ease of the process and the good resin-resin lamination properties of the base paper of the present invention (therefore, no adhesive is particularly required). 'A method called extrusion lamination or extrusion coating, in which the film is extruded from a V-die and simultaneously coated onto the original navy blue, is preferred. Laminate resin is 250°
It is selected from the following heat-resistant polyester polymers such as polyethylene terephthalate, polyethylene phthalate, and polybutylene terephthalate, and polyolefin polymers such as polypropylene and methylpentene polymers. The thickness of the laminate layer is made of heat-resistant cedar without any defects and maintains liquid resistance (water and oil resistance).

Determined by the amount of hair required to maintain a beautiful appearance, usually 6
~50μ@degrees. These v! 4.T lubricant in fat, *
It is possible to blend pigments, pigments, etc. to attack their properties.
For example, a printed pattern or the like can be applied to the surface of the paper layer on the outside of the plate before it is formed into a tray. In order to measure the adhesion of the printed laminate layer, the surface may be smoothed by calender treatment.

The base paper of the present invention obtained by constructing it as above has good adhesion to the resin to be laminated. During molding, there is no tearing or cracking of the paper layer even during deep drawing.

The paper layer does not lose its shape when exposed to moisture, heating, and cooling, and the paper layer peels off.
: No, it also exhibits excellent properties of no peeling from the laminate layer. Such a percentage characteristic was achieved for the first time by lζ of the present invention.

The base paper of the present invention can be used as a base paper for heat-resistant food containers and processed food containers, and as a laminate of the same, excellent quality can be provided, and the contents can be heated in an ovenable tray, open oven, 11-microwave oven, etc. A cooking tray, or similarly a tray or box for baking or steaming cakes, breads, etc.

Suitable for use as a container for boiling and steaming Uiro, manju, mochi sweets, etc., and contains raw materials and mixtures for these v4 products.

It is suitable for use as a packaging material for distribution containers for semi-A buried goods, cooked goods, and other frozen goods.

The present invention will be explained below with reference to Examples and Comparative Examples.

Example l Softwood kraft pulp 65 parts Hardwood kraft pulp 85 parts
After beating the pulp very lightly, a maleated petroleum resin-based cationizing agent was added to the pulp at a weight ratio of 2% and a polyamide-based bichlorohydrin-based wet paper strength agent of 0.8% was added to the pulp. The paper is made using a plated paper machine, and the paper-making process is 85 tsubo t85. or density 07
The properties of the octopus are shown in Table 1. The measurement was based on the JIS-P test method.

Example 2 A sizing agent based on styrene-maleic acid copolymer was added in an amount of 1.8% to the same pulp material as in Example 1 to obtain a sizing agent of 3:a.

Boot/m', b, 850 frr? , c
The characteristics of this product made from 400 sheets of paper were first determined.
Shown in the table.

Comparative Example 1 A base paper of 850 square meters was produced in the same manner as in Example 1, except that the sizing agent was added to the base paper of Example 1 at a concentration of 0°5. The properties of this product are shown in Table 1.

Comparative Example 2 The surface layer is a bleached kraft pulp layer made of laminated city board paper,
Table 1 shows the tenacity of examples d and e, in which the inner layer consists of a paper layer containing a relatively large amount of short fibers, such as bleached hardwood kraft pulp or pulp made from waste paper.

C Comparative Examples Examples 1-2 The base paper of Comparative Examples 1-2 was extruded and laminated with polyethylene terephthalate using a T-die using the g method, and a laminate with a resin m of 80μ thick was made, and this was drawn into a mold. Some corners are rounded due to the method of applying pressure to the surface 4 Approx. 151 @ approx.
The angle between the bottom and the side wall is about 105 degrees. The radius of curvature of the fold between the bottom and the side wall is about 5. The radius of curvature is about 5. rμ et al.
mold the plate.

Add the cooked gratin to this, freeze it immediately, package it, put it in the freezer for 2 months, put it in the oven toaster (
The sample was thawed and heated using an infrared heater for 4 minutes and then taken out. Table 2 shows the results of experimental observations regarding the characteristics of the laminate, its behavior during molding, and its behavior after it was loaded with contents and heated again.

Comparative Examples 9d and 9e had poor moldability, so a comparison was made with a dish with a bottom curvature radius of 2 cPR at an angle of 140° and a depth of 2 -, but even if the molding conditions were relaxed in this way, The results obtained did not change much.

In Table 2, when a cellophane adhesive tape was applied to both sides of a sample of the laminated adhesive Filb gourd cloth and the sample was forcibly peeled off by pulling it in both the front and back directions, only the resin layer was easily peeled off. If the adhesion is poor, the resin layer will partially peel off during use due to moisture and heat, making it unsuitable for practical use.

Comparative example 1. 2d had poor dense layer. In Comparative Example 2e, the dense layer between the paper surface and the resin layer was good, but the fi adhesion between the paper layers was poor, and the paper layer peeled off without any resistance in the above test.

Formability Fix caused the paper to crack and break at the curved portion and narrowed portion, and this tendency was observed in Comparative Example 2de.

The shape of the molded product is determined by the quality of the shape when left on the road after molding.

For 1m peeling during thawing, when the contents were manually frozen and removed from the freezer and left in a room at room temperature for 3 hours, the paper layer of the tray naturally peeled due to moisture. Comparison □Example 2de corresponds to No. 6〇 Discoloration and deterioration during heating. However, the smell got worse.

Deformation during heating t Those in which the plate twisted and bulged during heating were marked as x. The one-time event was designated as Δ.

As described above, the size and density of the base paper of the example are within the preferred range of the present invention, and as a result, it exhibits favorable physical properties such as strong wet G4 hardness, good folding resistance during heating, and good whiteness. On the other hand, the comparative examples have either or all of the size, density, elongation length and yellow ratio falling within the preferred range of the base paper of the present invention, and their physical properties include wet strength, folding resistance when heated, and whiteness. The effect of this is shown in the fact that the first shift of the degree is low.

The evaluation of the laminate products of Examples and Comparative Examples and the molded products thereof are as shown in Table 2, and only the products of Examples show the desired quality. It is clear that the comparative example has no practical value at all.

The outstanding features of the great invention base paper and its laminated products are obvious.

[Margin below]

Claims (1)

[Claims] ■ Made of a single paper layer and given a neutral size, with a size degree of 5
Laminate base paper for molding made of paperboard of 00 seconds or more. 2. When the size degree is 500 seconds or more, the following relationship is satisfied: A≧0.00882 (where A is the number of size degrees expressed in seconds, 11L, and B is the number of 1 on the base paper per 1 st? expressed in Durham). Base paper of Claim 1. 8. Made of a single layer of paper and given a neutral size, the size degree is 5.
Molding laminate with a thermoplastic resin layer on base paper for 00 seconds or more.