JP2001348793A - Roll for paper-making - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide roll for paper-making, excellent in transcribing property of a coating liquid without reducing physical properties and hardly attaching foreign materials such as paper powder, etc. SOLUTION: This roll for paper-making, installed with a coating layer consisting of at least >=1 layers of rubber like elastomer on its roll core is provided by characterized by using a polyurethane elastomer obtained by mixing and chemically bonding 3-10 pts.wt. ultrahigh molecular weight polyethylene powder having active groups such as OH and COOH groups with a cross-linking agent having NH2 or OH group based on 100 pts.wt. polyurethane prepolymer having NCO group as at least the uppermost surface of the above rubber like elastomer. Also, the above roll for paper-making is characterized by having >=1,000% NBS frictional resistivity at the uppermost layer, and further, by having 10-50 surface roughness (Rmax) at the surface of the uppermost layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a papermaking roll, and more particularly to a size applicator roll which is excellent in water repellency and abrasion resistance and requires a small friction coefficient, and foreign matter such as paper powder easily adheres to the roll surface. The present invention relates to a papermaking roll suitable for a smoother roll, a breaker stack roll, and the like.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for coated paper for printing, particularly coated paper for printing which is coated with a double-sided transfer type roll coater and which is excellent in flatness and smoothness. These coated papers are coated, for example, by passing a base paper through a nip of a size applicator roll, measuring a coating amount in advance, and transferring a coating liquid supplied onto the size applicator roll to the base paper. .

In a transfer-type roll coater such as a size applicator roll, when the coating liquid is transferred to the base paper, the coating liquid is cleaved between the applicator roll and the base paper, so that the coating surface is disturbed and the smoothness is impaired. Cheap. This is called an "orange peel pattern" and is one of the biggest problems of the transfer type roll coater. In addition, if the transfer of the coating liquid is not performed stably, the droplets when the coating liquid is cleaved fly on the paper surface, which impairs the quality of the coated surface.

Further, in the case where both sides of the base paper are coated through a plurality of applicator rolls, the base paper is pulled by both the applicator rolls. As a result, the peeling position from the applicator roll becomes unstable and causes uneven coating, which impairs not only the appearance of the coated paper but also the printability.

In a roll such as a smoother roll or a breaker stack roll, foreign matter such as paper dust easily adheres to the roll surface, the foreign matter such as paper dust accumulates on the roll surface and deteriorates the quality of the paper. There is.

Accordingly, the size applicator roll must be capable of stably transferring the coating liquid to the base paper without remaining on the roll, and the smoother roll and the breaker stack roll are those to which foreign matter such as paper powder is unlikely to adhere. There must be. Such size applicator roll,
Conventionally, rolls mainly coated with urethane rubber have been used for papermaking rolls such as smoother rolls and breaker stack rolls.

[0007]

Rolls coated with these urethane rubbers are excellent in abrasion resistance and chemical resistance, but as described above, the transfer of the coating liquid becomes unstable and coating unevenness occurs. And there is a problem that foreign matter such as paper dust is deposited on the roll surface. For this reason, attempts have been made to suppress coating unevenness and the accumulation of paper dust by improving the water repellency by mixing silicone oil in the urethane elastomer, but the silicone oil is extracted and the effect is shortened in a short period of time. There was a problem that it disappeared.

According to the present invention, there is provided a size applicator roll capable of stably transferring a coating liquid, having excellent water repellency and abrasion resistance, and having a small friction coefficient, and a smoother roll in which foreign matter such as paper powder is less likely to adhere to the roll surface. A roll for papermaking such as a breaker stack roll is provided.

[0009]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies, and as a result, have come to invent the papermaking roll of the present invention.

That is, the papermaking roll of the present invention is a papermaking roll in which at least one or more rubbery elastic covering layers are provided on a roll core, wherein at least the uppermost rubbery elastic body is NCO. OH groups and COOH per 100 parts by weight of a polyurethane prepolymer having a OH group
It is a polyurethane elastomer obtained by mixing 3 to 10 parts by weight of an ultrahigh molecular weight polyethylene powder having an active group such as a group with a crosslinking agent having an NH2 group or an OH group and chemically bonding them.

The papermaking roll of the present invention is characterized in that, in the papermaking roll of the above invention, the NBS abrasion resistance of the uppermost layer is 1000% or more.

Further, the papermaking roll of the present invention is characterized in that the surface roughness (Rmax) on the surface of the uppermost layer is from 10 to 50.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The papermaking roll according to the present invention is obtained by coating at least one or more rubber-like elastic material coating layers on a roll core, and at least the uppermost layer of the coating layers comprises: Ultra-high molecular weight polyethylene powder having active groups such as OH group and COOH group
It is coated with a rubber-like elastic body made of a polyurethane elastomer which is mixed with a polyurethane prepolymer having an NCO group together with a crosslinking agent having a group and chemically bonded thereto.

In the present invention, when an ultra-high molecular weight polyethylene powder having an active group such as an OH group and a COOH group is mixed with a polyurethane prepolymer having an NCO group, physical properties are not reduced due to chemical bonding of both, The water repellency increases, and the transfer rate when the coating liquid transfers from the roll to the base paper increases. At the same time as the transfer rate of the coating liquid increases,
A decrease in the smoothness of the coated surface due to cleavage of the coating liquid is suppressed. Further, foreign substances such as paper dust are less likely to adhere, and it is also possible to prevent foreign substances such as paper powder from accumulating on the roll surface and impairing the smoothness of the paper surface.

In the case of a coating roll, the quality of the coated paper surface is improved by setting the contact angle of the roll coating material to water at 90 ° to 140 °, preferably at 120 ° to 140 °. I know from experience.
The surface of the polyurethane elastomer has a surface roughness Rma.
If it is smaller than x10, the contact angle with water becomes smaller than 90 degrees, transfer of the coating liquid from the roll surface is deteriorated, and coating unevenness occurs. On the other hand, if the surface roughness exceeds Rmax50, the contact angle with water becomes larger than 140 degrees, the wettability of the roll surface is poor, and the coating liquid does not adhere to the roll surface, causing coating unevenness.

[0016]

Next, examples of the present invention will be described together with comparative examples.

Example 1 and Comparative Examples 1-2 The polyurethane elastomer constituting the coating layer of the papermaking roll was a polyurethane prepolymer "Adiprene L1" manufactured by Uniroyal Co. in all of Comparative Examples 1, 2 and 1.
00 "(trade name). Comparative Example 1 is a conventional polyurethane elastomer using only a crosslinking agent. In Comparative Example 2, a surface-inactive ultra-high molecular weight polyethylene powder “Miperon 221U” (trade name) manufactured by Mitsui Petrochemical Co., Ltd.
Was mixed with 3 parts by weight based on 100 parts by weight of “Adiprene L100” (trade name). Further, in Example 1, a special physical treatment was performed to modify the surface to make an ultra-high molecular weight polyethylene powder “VISTAM” manufactured by Composite Particles Incorporated having OH groups and COOH groups.
ER UH-1700 ”(trade name) to“ Adiprene L10
0 "(trade name) 3 parts by weight per 100 parts by weight.
In each of Comparative Example 1, Comparative Example 2, and Example 1, an aromatic diamine-based crosslinking agent, trade name “Cureamine MT” manufactured by Ihara Chemical Co., Ltd. was used.

With respect to the polyurethane elastomers of Comparative Example 1, Comparative Example 2 and Example 1 obtained by the above constitution,
Various comparative tests were performed. The results of the test are as shown in Table 1. The hardness (JIS A) and the tensile strength (kg / c
m2), elongation (%), tear strength (kg / cm), rebound resilience (%), compression set (%), and NBS abrasion resistance (%) were tested based on JIS K6301. . The coefficient of friction was measured using a surface property tester.

The test of the coefficient of friction was performed for the coefficient of static friction and the coefficient of dynamic friction. The test method used the surface property tester shown in FIG. A copy paper 2 is fixed as a contact object on a moving table 1, and a test roll 3 is placed on the copy paper 2. The test roll 3 used had an outer diameter of 30 mm and a length of 120 mm. An arm 6 having a fulcrum 5 is attached to the test roll 3 while applying 1000 g as a weight (W) 4 in the vertical direction. On the opposite side of the fulcrum 5 of the arm 6, a balancer 7 for removing the weight of the test roll 3 on the copy paper 2 is attached.
The tip of the arm 6 is attached to a load cell 9 provided with a measuring device 8.

In the above configuration, the moving table 1 is moved by one while the balancer 7 removes the weight of the test roll 3.
It was moved at a speed of 5 meters per minute, and the friction force (F gram) was measured by the load cell 9. As shown in FIG. 2, the analysis of the measurement is performed by plotting the measured frictional force into a graph, as shown in FIG. 2, from the frictional force at the start of the table movement (A gram) and the frictional force at the time when the table reaches parallel after the movement (B gram). The friction coefficient was determined by the following Expressions 1 and 2.

[0021]

(Equation 1)

[0022]

(Equation 2)

[0023]

[Table 1]

From Table 1, it can be seen that the NBS abrasion resistance of the roll coating material of the papermaking roll according to the present invention is dramatically improved as compared with the conventional product, and the roll life and the contamination of the paper product due to the roll coating material are reduced. It can be understood that the inconvenience due to is eliminated.

Examples 2 to 6 Next, as an ultrahigh molecular weight polyethylene powder having an OH group and a COOH group, "VISTAMER UH-17" was used.
The case where the blending amount of “00” (trade name) was varied was referred to as Example 2 to Example 6, respectively, and “VISTAMER UH-1” was used.
As a comparative example 1, a case where no “700” (trade name) was blended was subjected to a physical property comparison test. The test is based on JIS K63
01. The test results are shown in Table 2.

[0026]

[Table 2]

As is apparent from the above results, when the blending amount of the ultrahigh molecular weight polyethylene powder having an OH group and a COOH group is increased, the compression set becomes particularly large.
If the compression set becomes large, irregularities may occur on the roll surface during operation of the papermaking roll, or a problem such as increased heat generation may occur.Therefore, the amount of the ultra-high molecular weight polyethylene powder having an OH group and a COOH group is included. Is the limit of 10 parts by weight as a papermaking roll. Therefore, OH
The compounding amount of the ultrahigh molecular weight polyethylene powder having a group and a COOH group is in the range of 3 to 10 parts by weight based on 100 parts by weight of the urethane prepolymer.

Examples 7 to 11 and Comparative Examples 3 to 11 Next, the water repellency, that is, the contact angle to water, for stably transferring the coating liquid was examined. The sample was created as follows. In Comparative Example 3 and Comparative Examples 5 to 10, samples were prepared using “Adiprene L100” (trade name), and in Comparative Example 4, Comparative Example 11, and Examples 7 to 11, “Adiprene L1
00 "(trade name) ultrahigh molecular weight polyethylene powder having 100 parts by weight of OH group and COOH group
A sample was prepared by mixing 3 parts by weight of "ER UH-1700" (trade name).

The surface of the sample was polished so that the surface roughness was Rmax5 (Comparative Example 3 and Comparative Example 4) and Rm5, respectively.
amax10 (Comparative Example 5 and Example 7), Rmax15 (Comparative Example 6 and Example 8), Rmax30 (Comparative Example 7 and Example 9), Rmax40 (Comparative Example 8 and Example 10),
Rmax50 (Comparative Example 9 and Example 11) and Rmax
55 (Comparative Examples 10 and 11). The measurement was performed on the contact angles to water in each of the examples and comparative examples as shown in FIG. 3 by a screen projection method using a contact angle meter “CA-P type” manufactured by Kyowa Kagaku Co., Ltd. As shown in FIG.

[0030]

[Table 3]

As is clear from the above measurement results, in Examples 7 to 11, it was empirically found that the transfer of the coating liquid can be stably performed.
Although it is within the range of 0 degrees, it can be seen that Comparative Examples 3 to 10 are all lower than 90 degrees. In Comparative Example 11, the surface roughness Rmax was set to 55, but in this case, the contact angle with water exceeded 140 degrees. Therefore, the surface of the polyurethane elastomer preferably has a surface roughness Rmax of 10 to 50. If the surface of the polyurethane elastomer is smaller than the surface roughness Rmax10, the water repellency decreases, the transfer of the coating liquid from the roll surface deteriorates, and coating unevenness occurs. On the other hand, the surface of the polyurethane elastomer has a surface roughness R
If it exceeds max50, the water repellency increases, the wettability of the roll surface is poor, and the coating liquid does not adhere to the roll surface, resulting in uneven coating.

The results of tests performed to confirm the test results on an industrial scale are shown in the lower column of Table 3. The quality of the coated surface is obtained by visually observing the coated surface of a coated paper obtained by applying a roll of each material to an application roll of a transfer-type roll coater, and evaluating the quality on a three-point scale. or,
The adhesion state of the paper dust is obtained by visually observing the adhesion state of the paper dust after continuous operation of the roll of each material for the smoother roll for 24 hours.

As a result, in the transfer type roll coater using the rolls of Examples 7 to 11 in which the surface roughness Rmax was in the range of 10 to 50, the transfer of the coating liquid was stable, and the quality of the coated paper surface was low. It was in a very good condition without any damage. Examples 7 to 11, in which the surface roughness Rmax was in the range of 10 to 50, also gave good results on the adhesion of paper powder when applied to a smoother roll.

[0034]

The papermaking roll according to the present invention comprises a roll core and at least one coating layer of a rubber-like elastic material, wherein the rubber-like elastic material is added to 100 parts by weight of a polyurethane prepolymer having an NCO group. OH group and COO
By mixing 3 to 10 parts by weight of an ultrahigh molecular weight polyethylene powder having an active group such as an H group with a crosslinking agent having an NH2 group or an OH group to form a chemical bond, physical properties are hardly reduced. In addition, the papermaking roll according to the present invention has an appropriate water repellency, increases the transfer rate when the coating liquid is transferred from the roll to the base paper, and decreases the smoothness of the coated surface due to cleavage of the coating liquid. It is suppressed to do. Further, foreign substances such as paper dust are less likely to adhere, and it is also possible to prevent foreign substances such as paper powder from accumulating on the roll surface and impairing the smoothness of the paper surface.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a surface property tester.

FIG. 2 is a graph showing frictional force in frictional force measurement.

FIG. 3 is an explanatory diagram of a method of measuring a contact angle.

[Explanation of symbols]

 1: moving table 2: copy paper (contact object) 3: test roll 4: weight (W) 5: fulcrum 6: arm 7: balancer 8: measuring instrument 9: load cell

Continuing from the front page (72) Inventor Ichiro Umeda 3-4-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Mills Co., Ltd. (72) Inventor Chief Kawahara 3-4-2, Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Paper Stock In-house (72) Inventor Shigeru Suzuki 1 Nobesawa, Kaisei-cho, Ashigara-gun, Kanagawa Prefecture In-house company Meiji Rubber Kasei Co., Ltd. F-term (reference) 4L055 CG06 FA30

Claims (3)

[Claims] 1. A papermaking roll in which at least one or more rubbery elastic covering layers are provided on a roll core, wherein at least the uppermost rubbery elastic body is 100% by weight of a polyurethane prepolymer having an NCO group. A polyurethane elastomer obtained by mixing 3 to 10 parts by weight of an ultrahigh molecular weight polyethylene powder having an active group such as an OH group and a COOH group with a crosslinking agent having an NH 2 group or an OH group, and chemically bonding the mixture. A papermaking roll characterized by the following. 2. The papermaking roll according to claim 1, wherein the NBS abrasion resistance of the uppermost layer is 1000% or more. 3. The papermaking roll according to claim 1, wherein the surface roughness (Rmax) of the surface of the uppermost layer is 10 to 10.
50. A papermaking roll, which is 50.