JPS629011B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to extrusion coating methods. Conventionally, it is known to melt extrude low density polyethylene, ethylene-propylene random copolymer or crystalline polypropylene to coat paper, polyolefin film, metal foil, etc. However, when the polymer is melt-extruded and coated on paper, polyolefin film, metal foil, etc., the take-up speed is about 10 to 30 m/min. Extreme thickness unevenness occurs in the sheet, or in the case of crystalline polypropylene, the nettle becomes large, making it impossible to coat the sheet. Therefore, a method has been proposed in which low-density polyethylene is mixed with crystalline polypropylene and the resulting mixture is melt-extruded for coating. However, the above mixture has poor adhesion to paper, polyolefin film, metal foil, etc., and therefore easily peels off when coated as is, so an adhesive (anchor coating agent) is interposed between them. It must be covered. As a result of intensive research aimed at improving the above-mentioned drawbacks, the inventors completed this invention by using a combination of modifiers and modifiers described below. That is, this invention provides a crystalline polypropylene and a general formula; A compound represented by the general formula; A compound represented by the general formula; At least one compound (hereinafter referred to as a modifier) selected from the group consisting of compounds represented by the general formula; A compound represented by the general formula; Modified polypropylene obtained by melting and heating a mixture of at least one compound selected from the group consisting of the compounds shown in (hereinafter referred to as a modifier) and an organic peroxide, or crystalline polypropylene added thereto. An extrusion coating method characterized by melt-extruding the blended mixture and coating it on paper or polyolefin film (however, in the above general formula, R ₁ to _{R 6} are hydrogen atoms or methyl groups, and Me is a hydrogen atom or a methyl group, and Me is a metal atoms of Groups 1 to 3 and Group 8, l is an integer corresponding to the valence of Me, m and n are integers of 0 or 1). According to the method of this invention, the modified polypropylene or a mixture of the modified polypropylene and crystalline polypropylene is melt-extruded, and in the case of paper, the maximum
It can be taken off and coated at a speed of 250 m/min, or up to 200 m/min in the case of polyolefin in-films, with the extruded film or sheet having a small bond and an adhesive between them. Adhesive strength is sufficient even without it. The crystalline polypropylene used in this invention includes a crystalline homopolymer of propylene, a random copolymer or block copolymer of propylene and other α-olefins such as ethylene, butene-1, and mixtures thereof. Furthermore, examples include those in which up to about 20% by weight of other polyolefins, such as polyethylene, are mixed. The random copolymer preferably has a content of other α-olefins of about 5% by weight or less, and the block copolymer preferably has a content of other α-olefins of about 20% by weight or less. preferable. Among these, those having a melt flow index in the range of about 0.1 to 30 are preferred. Modified polypropylene can be obtained by melting and heat-treating a mixture of crystalline polypropylene, a modifier, and an organic peroxide, but the simplest melt-heat treatment is as follows:
A mixture of crystalline polypropylene, a modifier, a modifier, and an organic peroxide is melted and heated in an extruder. At this time, it is desirable that the crystalline polypropylene used does not contain any additives that may be decomposed by organic peroxides during melting and heat treatment to cause coloration and odor. Specific compound names of the modifier used in this invention include allyl glycidyl ether, 2-methyl-allyl glycidyl ether,
Sodium (meth)acrylate, Calcium (meth)acrylate, Magnesium (meth)acrylate, Zinc (meth)acrylate, Aluminum (meth)acrylate, Iron (meth)acrylate (), 4-
Examples include acroyloxyphenol, 4-(acryloyloxymethyl)phenol, 4-acryloyloxybenzyl alcohol, 4-methacryloyloxyphenol, 4-methacryloyloxybenzyl alcohol, 4-(methacryloyloxymethyl)benzyl alcohol, etc. . These modifiers can be used not only alone, but also as a mixture of two or more. Specific compounds of the modifier used in this invention include triallyl cyanurate, tri(2-methylallyl)cyanurate, 1,3,
Examples include 5-triacryloylhexahydro-S-triazine and 1,3,5-trimethacryloylhexahydro-S-triazine. These modifiers can be used not only alone, but also as a mixture of two or more. In this invention, since a modifier and a modifier are used in combination, a remarkable effect is achieved compared to the case where no modifier is used. The blending ratio of the modifier to the modifier is:
The ratio by weight is preferably in the range of 0.1 to 10.
In addition, the total blending ratio of the modifier and the modifier is 0.1 to 100 parts by weight of crystalline polypropylene.
A proportion of 5 parts by weight, especially 0.2 to 3 parts by weight is preferred. In addition, the organic peroxides used in this invention are those whose 1-minute half-life temperature is around the melting temperature of crystalline polypropylene, such as tert-butyl peroxybenzoate, dicumyl peroxide, and t-butyl peroxide. Butyl peroxylaurate, tert-butyl peroxyacetate, methyl ethyl ketone peroxide, 2,5-dimethyl-
Examples include 2.5-di-tert-butyl peroxyhexane, tert-butyl cumyl peroxide, tert-butyl peroxymale acid, and tert-butyl peroxylaurate. It is preferable that all of these organic peroxides be decomposed during the melting heat treatment in order to avoid decomposition of various additives or crystalline polypropylene added later. The melt flow index of modified polypropylene alone or a mixture of modified polypropylene and crystalline polypropylene supplied to the melt extrusion coating equipment is approximately 5.
Values in the range ~100 are preferred. When the melt flow index is greater than about 100, handling and film forming become difficult. When using a mixture of modified polypropylene and crystalline polypropylene, the melt flow index should be approx.
Modified polypropylenes having a melt flow index of 100 or higher can also be used if the melt flow index of the mixture with crystalline polypropylene is within the range of about 5 to 100.
The amount of crystalline polypropylene blended in this case is preferably 85% by weight or less. Mixtures containing more than 85% by weight of crystalline polypropylene tend to be difficult to take off and coat at high speeds. The melt flow index of modified polypropylene is determined by the melt flow index of crystalline polypropylene, the amount of organic peroxide added, the melting heat treatment conditions of the mixture, etc. Among these, the addition of organic peroxide It is easy and preferable to control the melt flow index of the modified polypropylene by controlling the amount. In addition, the temperature of the melt heat treatment is determined depending on the properties of the crystalline polypropylene used, and the time required is until all the added organic peroxide is decomposed and no organic peroxide is contained in the modified polypropylene. time is preferable. The amount of organic peroxide added cannot be set uniformly because it varies depending on the type of organic peroxide, the melt flow index of crystalline polypropylene, the melt flow index of the desired modified polypropylene, etc., but it is generally Specifically, it is about 0.01 to 10 parts by weight, preferably 0.02 to 3 parts by weight, per 100 parts by weight of crystalline polypropylene. If the amount added is less than the lower limit, the reaction between the crystalline polypropylene and the modifier will not occur sufficiently,
Therefore, the effect of the method of this invention cannot be obtained. Further, even if the amount added is greater than the above upper limit, no improvement in the effect of the method of the present invention is observed. Furthermore, conventionally known stabilizers, pigments, antistatic agents, other additives, fillers, etc. can be added to the modified polypropylene or mixture within the scope of the purpose of the present invention. Next, the modified polypropylene alone or a mixture containing up to 85% by weight of crystalline polypropylene is melt extruded, and the extruded molten film or sheet is coated in contact with paper or polyolefin film immediately before the nip roll. Ru. Here, the polyolefin film is a high-density polyethylene film, a polypropylene film, or a stretched film thereof. As the melt extrusion coating device, any device can be used as long as it can take off at high speed. According to the method of the present invention, the modified polypropylene or a mixture thereof blended with crystalline polypropylene can be melt-extruded and coated on paper or polyolefin at high speed, and in this case, the extruded film or sheet can be coated on paper or polyolefin at high speed. The netsuquin is small,
The adhesive strength between them is high, and the resulting film or sheet does not use a silane compound as a modifier, so it can be used for food packaging. Examples and comparative examples are shown below. Melt flow index (MI) followed ASTM D1238. In addition, the adhesive strength was determined by preparing a test piece according to ASTM D903, except that the width of the test piece was 1.0 cm, and then using an Instron universal tensile tester (manufactured by Instron Japan Co., Ltd.) at a tensile rate of 0.5. cm/
Measured at a temperature of 23°C. Parts indicate parts by weight. Further, the symbols in the following description mean the following compounds. A: Allyl glycidiether B: Zinc acrylate C: 4-methacryloyloxyphenol D: Triallyl cyanurate E: 1,3,5-triacryloylhexahydro-S-triazine F: 2,5-dimethyl-2 ,5-di-tert-butyl peroxyhexane Examples 1 to 12 Crystalline polypropylene (homopolymer) (MI
=15) After thoroughly mixing 100 parts with the type and amount of the modifier shown in Table 1, the modifier and the organic peroxide (F) in the amount shown in Table 1 in a Henschel mixer, supply it to the extruder. and react at a temperature of 200℃,
Modified polypropylene pellets of MI50 were produced. Cut this pellet into a slit with a width of 100cm and a slit width of 0.7~
The mixture was fed into an extrusion coating device equipped with a 0.9 mm die, and melt-extruded at 300° C. while gradually increasing the withdrawal speed, and coated on double-sided bleached kraft paper with a width of 100 cm. No pulsation, netquin value 15cm
Table 1 shows the maximum take-up speed and adhesive strength that could be coated under the following conditions. In all cases, the film thickness remained within the range of 25±2μ until the maximum take-up speed was reached.

[Table] In addition, the network value of Example 2 [(Dice width -
The product film width)/2] was 12.5 cm at a take-up speed of 240 m/min. Comparative Examples 1-2 Except for using MI9 (Comparative Example 1) and MI15 (Comparative Example 2) crystalline polypropylene (homopolymer) as they were instead of modified polypropylene,
In the same manner as in Example 1, when the take-up speed exceeded 10 m/min, pulsations began to occur, and when the take-up speed exceeded 25 m/min, the pulsations were so severe that extrusion coating could not be performed. Examples 13-16 Instead of the modified polypropylene pellets, the modified polypropylene pellets obtained in Example 2 were used.
MI9 crystalline polypropylene (homopolymer)
The same procedure as in Example 2 was carried out except that a mixture in which the amounts shown in Table 2 were uniformly blended was used. The results are shown in Table 2.

[Table] Comparative Examples 3 to 7 Polypropylene pellets of MI50 were obtained in the same manner as in Example 1, except that no modifier was added. Instead of modified polypropylene, the pellets were used alone (Comparative Example 3), or by blending MI5 crystalline polypropylene (homopolymer) with 80% by weight of the latter (Comparative Example 4).
60% by weight (Comparative Example 5), 40% by weight (Comparative Example 6), 20
% by weight (Comparative Example 7) except that a mixture was used. In both cases, as in Comparative Example 1, when the drawing speed exceeds 25 m/min, the pulsation becomes intense and extrusion coating occurs. I couldn't do it anymore. Examples 17-20 Crystalline polypropylene (homopolymer) (MI
=15) Modified polypropylene was prepared in the same manner as in Example 1 using 100 parts and the type and amount of the modifier shown in Table 3 and the organic peroxide (F) in the amount shown in Table 3. Pellets were produced. Cut this pellet into a slit with a width of 100cm and a slit width of 0.7~
It is supplied to an extrusion coating device equipped with a 0.9 mm die, melted and extruded at 300°C, and then melted and extruded to a thickness of 30 μm.
A 100 cm biaxially oriented polypropylene film was coated. The results are shown in Table 3.

[Table] Note that the netquin value of Example 18 is based on the withdrawal speed.
It was 14cm at 200m/min. Comparative Example 8 In the same manner as in Example 17 except that instead of the modified polypropylene, polypropylene of MI50 obtained in the same manner as in Example 17 without adding any modifier or modifying agent was used, the take-up speed was 25 m / When the time exceeded 1 minute, the pulsation became so intense that extrusion coating became impossible. Example 21 The same procedure as in Example 2 was carried out, except that instead of MI15 crystalline polypropylene, a mixture of 85 parts of ethylene-propylene random copolymer with an ethylene content of 3.5% by weight and 15 parts of low-density polyethylene was used. Modified polypropylene pellets were produced.
The pellets were used to coat double-sided bleached kraft paper as in Example 1. Maximum withdrawal speed
240m/min, adhesive strength 980g/cm, take-up speed 220m/min
At 1:00 a.m., the netquin value was 13cm. Example 22 The modified polypropylene pellets obtained in Example 21 were used to coat a biaxially oriented polypropylene film in the same manner as in Example 17. Maximum withdrawal speed
200m/min, adhesive strength 500g/cm, take-up speed 190m/min
The net measurement at the time of the test was 14 cm.

Claims (1)

[Claims] 1. Crystalline polypropylene, and a general formula; A compound represented by the general formula; A compound represented by the general formula; At least one compound selected from the group consisting of compounds represented by the general formula; A compound represented by the general formula; Melt-extrusion of modified polypropylene alone or a mixture of modified polypropylene and crystalline polypropylene obtained by melting and heating a mixture of at least one compound selected from the group consisting of the compounds shown in the formula and an organic peroxide. An extrusion coating method characterized by coating paper or polyolefin film. (However, in the above general formula, R ₁ to _{R 6} are hydrogen atoms or methyl groups, Me is a metal atom of Groups 1 to 3 and 8 of the periodic table, and l corresponds to the valence of Me. m and n are integers of 0 or 1).