JPH03174089A - Pulp containing mineral fiber based on cellulose fiber for use in manufacturing paper - Google Patents

Abstract

PURPOSE: To produce cellulose fiber-based paper pulp having bulkiness and a rigid feeling by mixing specific mineral fiber with cellulose fiber. CONSTITUTION: The objective pulp is produced by mixing (A) (preferably 2-15 wt.%) wool-like insulation mineral fiber (e.g. glass wool) having 3-8 μm average diameter with (B) cellulose fiber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to sheets based on cellulose fibers produced by a papermaking method.

More particularly, the invention relates to improvements in certain properties of products of this type.

[Conventional technology and issues]

The paper industry offers a very wide range of products in terms of intended use and product composition. In the field of printing papers, products must satisfy a large number of conditions. For example, 81 mechanical strength, dimensional stability, satisfactory openwork texture, good surface appearance, etc. Furthermore, conditions relating to the product itself must be considered in conjunction with conditions relating to the manufacturing method. Ingredients must be selected so that they can be manufactured under optimal conditions of cost and efficiency.

This set of factors includes the considerable control paper manufacturers have over the various components and their effects;
It also involves determining the most appropriate combination of each component, since the effects of each component may conflict with each other.

In printing paper, "feel" is a quality to which users are becoming increasingly sensitive. To a certain extent, this paper property is evaluated subjectively. A paper with a good feel is rated as a good quality paper. This corresponds to the mass bulk of the sheet.For the same weight, the thicker the paper, the better the feel.Users prefer bulkier paper. Irrespective of the subjective appearance, the improvement in feel is also explained by the greater "rigidity" of the sheet. A sheet with a relatively low basis weight is too soft even if it has sufficient mechanical strength. Even with such a low basis weight, it is important to have a certain degree of rigidity.

[Means to solve the problem]

The present invention therefore provides a new paper sheet product that provides particularly improved feel while being cost-satisfactory.

The production of paper sheet products according to the invention is carried out with a pulp based on cellulose fibers containing not more than 25% by weight of mineral wool, said wool being made from fibers exhibiting the dimensional properties of fibers made for insulation. ing.

In conventional papermaking technology, the purpose of using small amounts of mineral fibers is to improve the dimensional stability of the sheet, especially with respect to humidity. It appears that the objective pursued hitherto has always been that only fibers with known reinforcing properties have been proposed. In particular, these are so-called "textile" fibers, in other words mechanically produced fibers by mechanical drawing. In order to be incorporated into the material to be reinforced, these fibers are cut to specific lengths with white values of a few I or tens of I.

Textile fibers have better stiffness due to the regularity in diameter and length provided by their production method. Textile fibers also differ from mineral fibers made under other conditions in that their diameter is relatively large. Typically, the diameter of the "textile" fibers is 9-15 μm.

Due to the large diameter of textile fibers, their cost is also relatively high for the use in question. In other words, mixing, even in small quantities, adds considerably to the cost of the final product.

In contrast to the purpose sought by the present invention, it does not appear that these fibers were ever intended as a means of improving the feel of the paper sheets produced.

It should be noted that ``flame drawing'' of glass fibers is used for the purpose of improving certain properties of the paper sheet produced and for the purpose of facilitating drainage of the pulp during the manufacturing process.
It has been proposed to replace glass fibers produced by 1. Usually, the diameter of this fiber is very small, less than 3μ rings. These fibers are also not as precisely calibrated as textile fibers, but have a relatively constant diameter.

For textile fibers, cost limits their use. Also for textile fibers, there appears to have been no suggestion of use to improve the feel of manufactured sheets.

A feature of the invention is the use of mineral fibers that are normally produced by techniques used in the production of insulation fibers. The advantage of such fibers is that they can be produced in large quantities at relatively low cost. On the other hand, it is known that insulating fibers are less regular, especially in length, and have a certain brittleness when subjected to mechanical stress.

Given the expected role of mineral fibers mixed in during paper production, as well as the treatments that the fibers necessarily undergo during pulp and sheet preparation, thermal insulation fibers have so far been the least suited for this type of application. It is clear that this was not taken into account.

The inventors have discovered that the mineral fibers of the "insulating" type mixed in the papermaking pulp are not only crushed during the processing process, but also restored to dimensions sufficient for the use in question (iin or less); In particular, it has been shown that these fibers can provide an improved "feel" even when added in small amounts.

The reason for these properties is not fully explained. A comparison of the effects obtained with woven fibers and those obtained with very fine fibers suggests that the special structural features of the insulation fibers are in some way at play.

In particular, the lack of homogeneity in these fibers makes the sheet
In other words, irregular length and shape distribution may promote
It is believed that this aids in the entanglement effect that causes the structure of the sheet to "bulge" (sllel I).

In comparison, particularly straight and more rigid textile fibers do not appear to entangle in such a way.

Furthermore, very thin fibers are unlikely to have sufficient stress resistance to occupy the volume necessary to create this bulk, even when entangled.

Although the above explanation is only a hypothesis, the results found confirm this theory. The effect of fiber length is one example. If the fibers used are too short, the increase in feel will be reduced. On the other hand, if the length exceeds the boundaries of the fibers, there will be no further improvement. In both cases, the reason can be found in the suitability of the fibers to form a suitably entangled mass.

In this regard, it must be pointed out that the brittleness of the "insulating" fibers is not an obstacle to the application of the invention.

In the conventional methods of producing these fibers as defined below, the length of the fibers obtained is usually tens or hundreds of lengths. Needless to say, mineral wool, when added during the paper pulp manufacturing process,
Whether added at the refiner, refiner, or stu[box] stage, it undergoes an operation that breaks the fibrils into much shorter pieces.

Experiments have shown that in order to produce paper sheets with the desired quality, the length of added mineral fibers must be at least 0,
It was shown that 11 is preferable.

Considering, on the one hand, the other properties of the old fibers, in particular their diameter, and, on the other hand, the conditions of use, the pulp used should contain a high proportion of mineral fibers with a length of 0.2 to 0.6 old. It is preferable to have . In such conditions, when using "insulating" fibers, the disintegration of the fibers during the pulping process is an advantage since there is no need to perform a cutting operation before mixing into the pulp.

If it comes out of the manufacturing process and has a somewhat bulky tuft shape,
If it is possible to directly use glass wool that is 100% opaque, the process of reducing this wool to smaller dimensions facilitates mixing. In this sense, it is especially important to add glass fibers to the pulp, to facilitate their mixing into the pulp and to ensure uniform mixing.
"Nodu" prepared from "bulk wool"
It is advantageous to use le). For example 0.5-5I
After cutting the bulk wool, these nodules having dimensions of
It can be obtained by performing n). This type of operation
Even if the fibrils are to be divided, it is interesting that no irregularities are created. On the other hand, after the agglomeration operation the length of the fibers remains relatively large compared to that of the continuous fibers (of type <m) which are cut to be mixed into the pulp. These agglomeration operations differ from the chopping or cutting operations performed hitherto with regard to the material treated or application conditions and the results obtained.

Besides the fact that the length of the fibers is to some extent a result of pulp processing, it is also different from other previously used mineral fibers in terms of "insulation".
They are distinguished from fibers in their dimensional characteristics. In fact, the average diameter of insulation fibers has traditionally been 3 to 8 μm, more commonly 4 to 6 μm.

In the field of insulation, the diameter of the fibers is selected based on various considerations. For example, for the same mass of fibers, the smaller the diameter of the fibers, the greater the thermal resistance of wool. On the other hand, fibers that are too thin do not have the mechanical strength necessary to maintain wool quality over long periods of use. Added to these conflicting requirements are manufacturing cost considerations. It is clear that drawing fibers with very small diameters involves higher costs. To some extent, these various considerations also apply to the fibers used in papermaking pulp when improving feel. Bulking effect
effect) is important, the fibers must be sufficiently thin for a given mass and yet have good resistance to crushing.

The heat insulating fiber used in the present invention is obtained by centrifuging molten mineral material using known techniques. Optionally the material is centrifuged through a calibrated hole, or the molten material is simply dispersed in a more free manner. Centrifugal dispersion processes are often accompanied by the effect of pulling the fibers by a gas stream.

Preferred fibers for the present invention are made by techniques in which the centrifugal device acts as a mold or spinneret. Wools obtained by these techniques have the great advantage of being virtually free of non-fiber particles, in other words particles with dimensions larger than the inherent diameter of the fibers.

The first advantage of fiber production techniques consisting of centrifugation processes using gas to draw the fibers lies in the efficiency of these techniques in allowing a reduction in the cost of wool. Furthermore, it appears that the application of high velocity gas flow in the drawing process can produce fibers that are particularly suitable for mifelt production. This can be explained by the presence of substantial turbulence in these gas streams, resulting in the formation of highly "looped" fibers.

A method for obtaining these particularly preferred fibers is described in European Patent No. 9
No. 1.381 and No. 91,866.

The advantage of the technology described in these patents is that in all cases fibers with a variety of properties can be produced in large quantities at relatively low cost.

According to the invention, the commonly used wv& has an average diameter of 3 to 8 μm as described above.

However, for a particular wool and a particular average diameter, the respective fiber diameter can deviate from these average values. In each case, and whatever the average diameter of the fibers chosen, at least 80% by weight of the fibers making up the wool have a diameter of 3 to 8 μm. The discrepancy between one fiber and another of the same wool is largely due to the manufacturing process. The techniques described above produce fibers with relatively narrow histograms. in this way,
For wool, where the fibers have an average diameter of about 5 μm, 90% by weight of the fibers have a diameter of 3.5 to 7 μm.

For applications of the present invention, the greater the spread of fiber diameters, the more important it is to avoid the presence of non-fibrous grains. From this point of view, the fibers obtained by the above-mentioned technique are
It's absolutely excellent. The proportion of non-fibrous material in insulating wool is much lower than that obtained by other technologies.

The introduction of mineral fibers into papermaking compositions can reduce up to 2% of the dry matter.
Optionally limited to up to 5% by weight. Although it is possible to increase the amount of mineral fiber, it is not only costly, but also the resulting paper has special properties that are undesirable for printing. Therefore, if the mineral fiber content is too high, there will be an undesirable increase in porosity.

Furthermore, if improved feel is important even for low mineral fiber contents, 2% is the lowest amount deemed necessary to achieve any significant results.

Preferably, the amount of mineral fibers is between 2 and 15% by weight on dry matter in the pulp used.

What should be improved is the feel or substance.
If e), another way to arrive at the exact amount of mineral fiber required is to establish this as a function of the minimum improvement required. The minimum useful increase can be determined to be about 3%. The minimum amount of fibers introduced according to the invention preferably provides an increase in feel of at least 3% for paper obtained from a pulp that is the same except for these mineral fibers! "tP-FUS The invention also relates to a paper sheet produced on the basis of cellulose fibers containing mineral fibers of the insulating type, in which the sheet has an improved feel. The paper sheet so produced has In particular, it is the inclusion of mineral fibers as the only additive that can improve the feel in the composition.It must be emphasized that other additives increasing the volume or basis weight are known in this regard. These additives are particularly useful for “light” materials such as microspheres.
Also included are additives called fillers. A disadvantage of such additives, apart from their often high cost, is that they result in a substantial reduction in mechanical properties such as burst strength or tear strength. A significant advantage of using insulating fibers to improve feel under the conditions of the invention is that the mechanical properties in question are not significantly affected.

〔Example〕

EXAMPLES The present invention will be explained in detail by examples below, but the present invention is not intended to be limited thereto.

Samples were prepared by adding glass wool of various quality and quantity.
Made from crude kraft pulp refined to °SR.

The glass fibers are first soaked in water to facilitate mixing.
It was then added to the pulp and stirred. The mixture was stirred for 2 minutes in a Lhomargy defibrillator (
de-fiberiB unit).

The seat is a Nople wood bench (Nobel and W
Finished with wood bench), NFQ 50-00
Based on 2 specifications, a sheet of 150 g/l was obtained.

Tests were conducted with increasing amounts of fiber incorporated. Comparisons were confirmed by control sheets.

A sheet according to the invention (No. 2>, whose insulation fibers have an average diameter of 4 μm) was compared with a sheet (No. 1), whose fine fibers also have a diameter of 1 μIff.

To check feel or ground (cc/g), use NFQ0
The results of measurements of each sheet based on the 3-016 (ISOR534) standard are as follows.

Glass Fiber % O2510 11,371,371,391,45 21371,501,651,68 When glass fiber is added under the conditions of the present invention, the amount is only 2
%, the texture or feel also increased. The increase in feel obtained by adding insulating type fibers according to the invention is advantageous when compared to that of fine fibers. The improved feel for 10% fine fibers is less than for 2% insulating fibers.

These tests show that the improved feel is not uniform, being faster at lower loadings and slower at loadings greater than 5% by weight.

NFQol- performed simultaneously on the prepared sheets.
053 (ISO 2758) standards showed that the ones with added insulation fibers were essentially better than those with fine fibers.

In addition, the dimensional stability of the sample with glass fiber added (DIN
53130 and NFC26131) were also observed to be improved.

Printing without mineral fillers - using writing pulp,
A series of other tests were conducted. The pulp is a mixture of bleached kraft pulp (66% Socel, 34% Iggesund) refined to 28°SR.

The seat is a Noble wood bench (Noble and
80 g/m2 using a flood bench).

As in Example 1, the fibers used were fine fibers (
3), insulating fibers (4), insulating fibers sized by 0.8% with polyvinyl alcohol (5), and insulating fibers sized by 0.8% with starch (5);
6).

The results of measuring the feel from these various tests are shown in the following equation.

3 1.5 1.65 1.
724 1.5 1.94
2.145, 1.5 1.81
2.086 1.5 1.88
2.20 The trend found in the sample of Example 1 was confirmed in other types of sheets. The increase in feel in all samples (4, 5, 6) according to the invention was substantial, with the improvement in the fine fiber version being very small.

Furthermore, as mentioned above, the dimensional stability of sheets obtained using heat-insulating fibers was improved mainly when a large amount was blended, and the decrease in mechanical strength was not so large.

The measurement results of dimensional stability at relative humidity of 65 to 95% are shown in the following table as elongation (%).

Glass fiber% 010 3 0.44% 0.32%4
0.44% 0.3 %5
0.44% 0.29%6
Mineral filler consisting of 0.44% and 0.29% calcium carbonate [Commercial product: Hydrocarb (Hyc
The test of Example 2 was repeated with the addition of lrocarb) 60). Mineral filler was added at 10% of the pulp weight.

The measurement results for feel and dimensional stability are shown in the table below.

The samples were 3c, 4c, 5c, and 6C, respectively.

3c 1.57 1.66
1.84c 1.57 1.85
1.985c 157 1',
93 1.91Be 1.57
2.03 2.02 Dimensional Stability Ni Glass Fiber% 010 3c O, 36% 0.36% 4c
O, 36% 0.29%5c
0.36% 0.28%6c O,36
% 0.29% A series of tests were conducted with a "print-write" type pulp without added mineral filler. The pulp is a blend of bleached kraft pulp (60% beech wood, 40% resinous) refined to 40''XSR.

J:P-@--
It was made to weigh 70 g 7 m'' at a speed of 1 minute.

The fibers used are as follows: - Fine fibers with an average diameter of 1 μm (No. 7) - Average diameter of 4 μm
Insulating fiber (No. 8) with a diameter of 11 μm (No. 9) A textile fiber cut into 5 pieces with a diameter of 11 μm (No. 9) The measurement results of feel and dimensional stability are shown in the following table.

Sample No., Control 7 8 9 Glass fiber% 0 5 5 5 Feel (cc/8) 1
．． 69 1.78 1.84 1.67゜Relative humidity 20
Dimensional stability at ~80%: running direction (%) 0.3
5 0.33 0.25 0.32 Lateral force method (%) 0
．． 83 0.80 0.64 0.69 These tests show that the results obtained under the conditions according to the invention (sample 8) are good for feel and dimensional stability. This improvement @ fine fiber (sample 7) and textile fiber (sample 9)
This was confirmed by comparison with

Furthermore, these tests conducted under conditions close to pilot line or industrial production confirmed the results shown in the bench tests.

Claims (8)

[Claims] (1) A papermaking pulp based on cellulose fibers and containing mineral fibers, characterized in that the mineral fibers exhibit properties of heat-insulating fibers, such as having an average diameter of 3 to 8 μm and a wool-like appearance. (2) The papermaking pulp according to claim 1, wherein the mineral fiber is contained in an amount of 2 to 25% by weight based on the dry ingredients. (3) Papermaking pulp according to claim 1 or 2, wherein at least 80% by weight of the mineral fibers have a diameter of 3 to 5 μm. (4) The papermaking pulp according to claim 1 or 2, wherein the mineral fibers have an average diameter of 4 to 6 μm. (5) The papermaking pulp according to any one of claims 1 to 4, wherein the mineral fiber content is 2 to 15% by weight based on the dry ingredients. (6) Papermaking pulp according to claim 1, wherein the wool-like fibers are added in small pieces of 0.5 to 5 mm. (7) For papermaking according to any one of claims 1 to 6, characterized in that the mineral fibers added are glass fibers obtained by a technique comprising centrifugal treatment and stretching under a gas flow. pulp. (8) A sheet obtained from the pulp according to any one of claims 1 to 7, wherein the mineral fibers have an average length of 0.2 to 0.6 mm.