JPS6173779A - Paper adhesive - Google Patents

Abstract

PURPOSE:A paper adhesive showing excellent adaptability to coating even on a high-speed laminating machine, obtained by incorporating a partially saponified polyvinyl alcohol into an ethylene-vinyl acetate polymer emulsion prepared by using a PVA as protective colloid. CONSTITUTION:An emulsion of an ethylene-vinyl acetate copolymer containing 5-40wt% styrene is prepared by using 2-10wt%, based on vinyl acetate, polyvinyl alcohol having an average degree of polymerization of 200-3,000 and an average degree of saponification of 80-96mol% as protective colloid. This emulsion, as a base emulsion, is mixed with 1.6-40pts.wt., based on 100pts.wt. solid of the base emulsion, partially saponified polyvinyl alcohol having an average degree of saponification of 80-93mol%, thus giving an objective paper adhesive having a viscosity at 20rpm with a Brookfield BH viscometer of 1,000-20,000 and a thixotropy index (TI), calculated by the formula, of 0.3 or lower.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an adhesive for paper processing, and more specifically, an ethylene/vinyl acetate copolymer emulsion type that exhibits excellent coating suitability even when used in high-speed laminating machines. The present invention relates to adhesives for paper processing.

(Prior art) Ethylene-vinyl acetate copolymer emulsion produced using polyvinyl alcohol as a protective colloid has not been used as a paper adhesive for bonding paper to base materials such as paper, aluminum boxes, and plastics. well known.

For example, Japanese Patent Publication No. 49-26504 discloses an ethylene-vinyl acetate copolymer emulsion produced using completely saponified polyvinyl alcohol and partially saponified polyvinyl alcohol, which is 6 revolutions per 600 revolutions measured by a B-type viscometer. The ratio of measured values is 1.8 or less (TI is 0.25
5 or less) have been proposed/QX.

Furthermore, in Japanese Patent Publication No. 49-26518, saponification degree of 90~
TI
Adhesives with a value of 0.4 or less are suggested.

(Problems to be Solved by the Invention) In recent years, there has been a strong demand for faster bonding lines in order to improve productivity. In response to this demand, processing machines have significantly advanced and, for example, high-speed laminating machines with line speeds of 200 m/min or more have been developed. However, when the above-mentioned known adhesive is used in such a high-speed laminating machine, a so-called gum-up phenomenon occurs approximately 1 to 2 hours after the start of operation, so the operation must be interrupted and the coating machine must be cleaned each time. I had to drive it again,
In some cases, this led to a decrease in productivity.

As described above, conventional adhesives do not have sufficient coating suitability for high-speed laminating machines, and the development of improved products has been desired.

(Means for Solving the Problems) In view of the above-mentioned current situation, the present inventors have developed an ethylene film that does not cause the gum-up phenomenon even when used in the above-mentioned high-speed laminating machine and exhibits excellent suitability for development.・As a result of intensive research to find a vinyl acetate copolymer emulsion type adhesive,
An adhesive obtained by using a specific ethylene/vinyl acetate copolymer emulsion as a base emulsion and adding a specific amount of specific polyvinyl alcohol to the base emulsion and having physical properties in a specific range also meets the above purpose. The inventors have discovered that it exhibits extremely excellent coating suitability and has a fast setting speed, leading to the present invention.

That is, the present invention has, as a base emulsion, an average degree of polymerization of 200 to a, ooo, and an average degree of saponification of 80 to 9.
Using an ethylene/vinyl acetate copolymer emulsion in which 6 mol% polyvinyl alcohol is used as a protective colloid and 2 to 10% by weight based on vinyl acetate, and the ethylene content in the copolymer tends to be 5 to 40% by weight. , obtained by adding 1.6 to 40 parts by weight of partially saponified polyvinyl alcohol having an average saponification degree of 80 to 93 mol% to the emulsion, based on 100 parts by weight of the solid content of the emulsion, and whose BH type viscosity Viscosity at 20 rotations of the meter is 1.000~
The present invention provides an adhesive for paper processing, which is characterized in that it has a thixotropy index (TI) of 20.000 CpS1 and a thixotropy index (TI) calculated by the following formula of 0.8 or less.

The ethylene/vinyl acetate copolymer emulsion as the base emulsion used in the present invention contains polyvinyl alcohol as a protective colloid with an average degree of polymerization of 200 to 3,000 and an average degree of saponification of 80 to 96 mol% relative to vinyl acetate. -10% by weight, and the ethylene content in the copolymer is 5-40% by weight.

If polyvinyl alcohol is outside the above range,
For example, if the average degree of polymerization is less than 200, the stability of the emulsion itself will be poor even though it has the viscosity necessary as an adhesive, while if the average degree of polymerization exceeds a, ooo, the viscosity of the emulsion will increase extremely. Therefore, workability is significantly reduced during the production and use of the emulsion. Furthermore, if the average degree of saponification is less than 80 mol% or more than 96 mol%, the stability of the emulsion is poor.

In addition, if the amount of polyvinyl alcohol used is less than 2% by weight based on vinyl acetate, the stability of the emulsion will be poor, and if it exceeds 10% by weight, the state of adsorption of polyvinyl alcohol to emulsion particles in the polymerization system will deteriorate. Perhaps because it is extremely complex, it is not possible to stably obtain an emulsion with a constant viscosity.

Furthermore, if the ethylene content of the copolymer is less than 5% by weight, the minimum film forming temperature will be 5°C or higher, so sufficient adhesive strength will not be obtained in winter; If it exceeds the limit, the cohesive force of the adhesive will decrease,
If force is applied to the adhesive surface, for example, if a base material with a strong repulsive force is used, this may cause peeling problems, which is not preferable.

The adhesive of the present invention uses an ethylene/vinyl acetate copolymer emulsion as a base emulsion, but the manufacturing method itself is not particularly limited as long as it is made of the above-mentioned specific copolymer emulsion. In addition to ethylene and vinyl acetate, vinyl esters other than vinyl acetate such as vinyl propionate, vinyl butyrate, vinyl laurate, vinyl tertiary higher fatty acids, vinyl chloride, acrylic acid, methacrylic acid, crotonic acid, itaconic acid, Uses a copolymer emulsion in which one or more of unsaturated carboxylic acids such as maleic acid, esters and anhydrides of unsaturated carboxylic acids are copolymerized in an amount of 20% by weight or less based on vinyl acetate. You can also.

The adhesive of the present invention is prepared by adding 1.6 to 40 parts by weight of polyvinyl alcohol having an average degree of saponification of 80 to 93 mol% to the above-mentioned specific copolymer emulsion based on 100 parts by weight of the solid content of the base emulsion. It is something that can be obtained,
Viscosity at 20 rotations of a B-type rotational viscometer (hereinafter referred to as f3 H-・
(abbreviated as 20) is 1,000 to 20,00 ocps
It is limited to those with a TI of 0.8 or less.

If you use polyvinyl alcohol for post-addition with an average saponification degree of less than 80 mol%, gum-up will hardly be prevented, whereas if you use polyvinyl alcohol with a saponification degree of more than 98 mol%, TI is O,
Since it exceeds aO, not only is the flow property unsuitable as an adhesive, but also gum-up is almost prevented, resulting in extremely poor coating suitability for high-speed laminating machines.

Polyvinyl alcohol, which is added later, is usually added in the form of an 80% by weight or less aqueous solution due to its ease of dissolution, but the amount added as polyvinyl alcohol is 1.6 parts by weight per 100 parts by weight of the solid content of the base emulsion. If the amount is less than 40 parts by weight, gum-up cannot be prevented, whereas if it exceeds 40 parts by weight, the setting property of the adhesive will be poor because the amount of water in the adhesive will increase due to the addition of the aqueous polyvinyl alcohol solution.

In addition, if BH-20 is less than 1,000 CpS, the viscosity is too low, and when applying adhesive to the base material (paper) with a coater, it will not adhere (adhere) to the roll and sufficient coating will not be possible. Moreover, if it exceeds 20,000 CpS, the fluidity will be significantly reduced and the workability will be significantly reduced.

In addition, when the TI exceeds 0.3, a phenomenon caused by the adhesive bulges up in the areas where the coater applies shear occurs, causing the surface layer to dry and gum up. In addition to the problem, when laminating paper materials with low basis weight (low density) at high speed, the viscosity of the adhesive decreases significantly when laminating with a high-speed coater, causing the adhesive to penetrate into the paper material. , sufficient adhesion performance will not be developed.

As mentioned above, the adhesive of the present invention is obtained by adding a specific amount of specific polyvinyl alcohol to a specific base emulsion. , various organic solvents such as perchlorene, trichrene, dichlorobenzene, and l-dichlorobenzene, various thickeners such as hydroxyethyl cellulose, methyl cellulose, and sodium polyacrylate, and inorganic fillers such as calcium carbonate, talc, clay, and titanium oxide, etc. Furthermore, various additives such as antifoaming agents, dispersants, and antifreezing agents can also be added.

(Effects of the Invention) Even when the adhesive of the present invention thus obtained is used in a high-speed laminating machine, no gum-up phenomenon occurs, and it exhibits extremely excellent coating suitability and brings about a remarkable improvement in productivity.

(Examples) The present invention will be specifically described below with reference to Examples, but the present invention is not limited thereto.

Example 1 As a protective colloid, polyvinyl alcohol with an average degree of polymerization of 500 and an average degree of saponification of 88 mol% and an average degree of polymerization of 1
Ethylene-vinyl acetate copolymer emulsions were prepared using 4 and 1% by weight of polyvinyl alcohol with an average degree of saponification of 88 mol % based on vinyl acetate, respectively. Solid content; 55% by weight, BH-20; 1950 c
ps1'ri: 0.42, ethylene content in the copolymer: 20% by weight.

This emulsion is used as a base emulsion, and 20 parts by weight of partially saponified polyvinyl alcohol having an average degree of saponification of 88 mol% and an average degree of polymerization of 500 is added to 80 parts by weight of a 0/l aqueous solution to 100 parts by weight of the solid content of the emulsion. Added to emulsion to prepare adhesive.

The adhesive has a solids content of 48% by weight and is BH-20;
It had physical properties of 1480CpS, Tl: 0.11. Next, a performance evaluation test as an adhesive was conducted using the method described below, and the results are shown in Table 1.

After the film re-emulsifiable adhesive was formed into a film on a glass plate, it was immersed in water and the state of the film was observed one hour later. A film in which the film shape has collapsed is marked as having re-emulsifying property and is marked with an O mark, and a film in which the film form does not collapse even if there is a whitening phenomenon is marked as having no re-emulsifying property and is marked with an X mark.

Set time: Coat the adhesive on kraft paper with Wet 6mils, immediately cut about half of the kraft paper into strips, stack it on the coated surface, stick it together, and then peel off the strips every 3 seconds. The time until the paper material breaks was measured.

New sack machine N-5SM-N-5S made by Horie Co., Ltd. for roll suitability
A small cardboard box was pasted together using an S-type pasting machine.

Adhesives that did not cause gum up after continuous operation for 6 hours at a line speed of 450 m/min were judged to have passed.

Example 2 To the same base emulsion as in Example 1, 8.5 parts by weight of partially saponified polyvinyl alcohol having an average degree of saponification of 88 mol% and an average degree of polymerization of 1,700 was added to 100 parts by weight of the solid content of the emulsion. The adhesive was prepared by adding it as a wt % aqueous solution.

The adhesive has a solids content of 52% by weight and is BH-20;
It had physical properties of 2,940 cps, TI; 0.2B. Next, a performance evaluation test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Example 8 For the purpose of thickening and improving drying properties, an adhesive was prepared by adding 10 parts by weight of percrene to 100 parts by weight of the adhesive obtained by carrying out the same procedure as in Example 1. The adhesive has a solid content of 44% by weight, and has a BH-20:2.0
90CpS1TI; It had a physical property value of 0.27.

Next, a performance evaluation test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Example 4 An adhesive was prepared by adding 10 parts by weight of toluene and 10 parts by weight of calcium carbonate to 100 parts by weight of an adhesive obtained in the same manner as in Example 1. The adhesive has a solids content of 49% by weight, B-20; 4970CpS,
It had physical properties of TI: 0.17.

Next, a performance evaluation test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Example 5 As protective colloids, polyvinyl alcohol with an average degree of polymerization of 1,700 and an average saponification degree of 88 mol% and polyvinyl alcohol with an average degree of polymerization of t, soo and an average saponification degree of 96 mol% were added to vinyl acetate, respectively. 8% by weight
Solid content: 55% by weight, BH-20; 3,200cp
s1TI: 0.2B, ethylene content in copolymer: 15
A weight percent ethylene/vinyl acetate copolymer emulsion was prepared.

This emulsion is used as a base emulsion, and the average degree of saponification is 88 based on 100 parts by weight of solid content of the emulsion.
An adhesive was prepared by adding 2 parts by weight of partially saponified polyvinyl alcohol having a mole % average degree of polymerization of 1.700 to a 20 weight % aqueous solution to the base emulsion.

The adhesive has a solids content of 58% by weight and is BH-20;
It had a physical property value of 3,980, TI; 0.17. Next, a performance evaluation test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 1 The same base emulsion as in Example 1 was used as is as an adhesive. The performance evaluation results are shown in Table 1.

Comparative Example 2 Into the same base emulsion as in Example 1, 8.5% of completely saponified polyvinyl alcohol with an average degree of saponification of 96 mol % and an average degree of polymerization of 1.400 was added to 100 parts by weight of the solid content of the emulsion. A 15% by weight aqueous solution was added to prepare an adhesive. The adhesive has a solids content of 50% by weight.
and B H-20; 2,600CpSTI; 0.
It had a physical property value of 52. Next, a performance evaluation test similar to that in Example 1 was conducted, and the results are shown in Table 1.

Comparative Example 8 The same base emulsion as in Example 1 was added with an average saponification degree of 88 mol% based on 100 parts by weight of solid content of the emulsion.
An adhesive was prepared by adding 1.2 parts by weight of partially saponified polyvinyl alcohol having an average degree of polymerization of 1,700 as a 20% by weight aqueous solution. The adhesive has a solids content of 54% by weight, B H-20; 2,140 CpS, T I;
It had a physical property value of 0.40.

Next, a performance evaluation test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 4 The same base emulsion as in Example 1 was added with an average saponification degree of 88 mol% based on 100 parts by weight of solid content of the emulsion.
An adhesive was prepared by adding 46 parts by weight of polyvinyl alcohol having an average degree of polymerization of 1,700 as a 20% by weight aqueous solution. The adhesive has a solids content of 86% by weight and is BH-2
It had physical property values of 0: 14080CpS and TI: 0.09. Next, a performance evaluation test was conducted in the same manner as in Example 1, and the results are shown in Table 1.

Comparative Example 5 The same base emulsion as in Example 5 was used as is as an adhesive. The performance evaluation results are shown in Table 1.

Comparative Example 6 Protective colloid with average polymerization degree of 500 and average saponification degree of 8
8 mol% polyvinyl alcohol and average degree of polymerization 1,
700, polyvinyl alcohol with an average saponification degree of 88 mol%, respectively, 4 and 4.4% by weight based on vinyl acetate.
using, solid content 52% by weight, BTI-20; 8.80
An ethylene/vinyl acetate copolymer emulsion was prepared with 0 CpS, TI: 0.49, and ethylene/vinyl acetate content in the copolymer: 20% by weight.

Next, a performance evaluation test was conducted using the emulsion as it was as an adhesive. The results are shown in Table 1.

This adhesive is the same as the adhesive of Example 2 in the type and amount of polyvinyl alcohol used, but differs in that the entire amount of polyvinyl alcohol was used during polymerization. These differences make this adhesive TI
was significantly increased, and the performance evaluation results also showed that the oral aptitude was poor.

Comparative Example 7 Protective colloid with average degree of polymerization of 500 and average degree of saponification of 8
8 mol% polyvinyl alcohol and average degree of polymerization 1,
800, polyvinyl alcohol with an average saponification degree of 96 mol% was used at 8.5 and 4.5% by weight, respectively, based on vinyl acetate, solid content: 55% by weight, BH-20: 8.80
0CpS, TI; 0.25, ethylene content i in the coelectric material;
A 20% by weight ethylene/vinyl acetate copolymer emulsion was produced.

Next, a performance evaluation test was conducted using the emulsion as it was as an adhesive. The results are shown in Table 1.

*1) Protective colloid 2 The numbers in Table 2 are percentages based on vinyl acetate. *Additional polyvinyl alcohol: The numbers in the table indicate weight % based on 100 parts by weight of the solid content of Pace Emulsion.

*8) Other additives: The numbers in the table indicate the weight % based on the mixture of the base emulsion and additionally added polyvinyl alcohol.

*4) Roll aptitude: Values within 0 lead to gum up (2
1 complete) 5. Target of correction 11-1m! , , L”1.-r
T procedure amendment (voluntary) Manabu Shiga, Commissioner of the Patent Office 1 Case description 1982 Patent application No. 196288 August 2 Title of invention Paper processing adhesive 3, amend it! Relationship with the patent applicant's case Patent applicant address 5-15 Kitahama, Higashi-ku, Osaka Name (20
9) Hijikata, Representative of Sumitomo Chemical Industries, Ltd.
Take 4, Agent address: 5-15-6 Kitahama, Higashi-ku, Osaka, Contents of amendment: (1) "Low stability," on page 6, line 17 of the specification.
is corrected to "less stable."

(2) "Adhesive" on page 12, line 19 of the specification is corrected to "adhesive".

(3) [B-20J on page 14, line 17 of the specification]
I (corrected to -20J.

(4) r 8.980 in the 1st % line of page 15 of the schedule.”
amended to “8.980cI) as J.

(5) Page 20 of the specification (Table-1) 6th line from the bottom [
J Correct IJ to [TIJ.

that's all (2 complete)

Claims (1)

[Claims] As a base emulsion, the average degree of polymerization is 200 to 3.0.
Polyvinyl alcohol with an average saponification degree of 80 to 96 mol% is used as a protective colloid in an amount of 2 to 10% by weight based on vinyl acetate, and the ethylene content in the copolymer is 5 to 4% by weight.
Using an ethylene/vinyl acetate copolymer emulsion with a concentration of 0% by weight, the emulsion has an average saponification degree of 80 to 80%.
It is obtained by adding 1.6 to 40 parts by weight of 98 mol% partially saponified polyvinyl alcohol to 100 parts by weight of the solid content of the emulsion, and the viscosity at 20 revolutions on a BH type viscometer is 1. 000 to 20,000CpS, and thixotropy index (TI) calculated by the following formula
An adhesive for paper processing, characterized in that: is 0.3 or less. TI=log_1_0 (viscosity at 2 revolutions/viscosity at 20 revolutions)