WO2008036307A2

WO2008036307A2 - Method of making a fibrous web with improved retention of strength additive

Info

Publication number: WO2008036307A2
Application number: PCT/US2007/020285
Authority: WO
Inventors: Marc D. Koskinas; Mark G. Cupta; Christopher L. Wilkins; James S. Strickler
Original assignee: Celanese International Corp
Current assignee: Celanese International Corp
Priority date: 2006-09-19
Filing date: 2007-09-19
Publication date: 2008-03-27
Anticipated expiration: 2009-03-19
Also published as: WO2008036307A3

Abstract

A method for making fibrous webs with improved strength by adding agglomerated polyvinyl alcohol resin in the wet-end of a papermaking process. The agglomerated polyvinyl alcohol resin is readily retained in the paper during the formation of the web, providing for paper with improved strength properties.

Description

METHOD OF MAKING A FIBROUS WEB WITH IMPROVED RETENTION OF STRENGTH ADDITIVE

Technical Field

The present invention relates generally to a method of enhancing the retention of strength resins which are added to the wet-end of papermaking processes. In particular, the method of the invention enhances the mechanical retention of polyvinyl alcohol (PVOH) resin in a fibrous web by agglomerating the polyvinyl alcohol particles and combining the agglomerated particles with the papermaking furnish.

Background of the Invention

Strength additives are routinely added to fibrous webs in papermaking processes to increase the strength properties of the finished web. Some additives are combined with the paper in the wet-end portion of the process, where they are mixed with the fiber slurry, and subsequently integrated into the fibrous mat during web formation.

The use of polyvinyl alcohol as a wet-end additive in paper making is known in the art. United States Patent No. 2,402,469 to Toland et al. discloses a papermaking process where water swellable polyvinyl alcohol particles are added to a pulp slurry. According to Toland et al., the polyvinyl alcohol resin improves the strength of the paper. United States Patent No. 4,865,691 to White also teaches a method of strengthening fibrous materials by using polyvinyl alcohol as a wet-end additive. The White reference advocates the use of super-hydrolyzed polyvinyl alcohol particles, because they have a high hydrated bulk volume which promotes retention of the particles in the fibrous web.

Crosslinked polyvinyl alcohol has also been used as an additive in papermaking processes. United States Patent No. 5,147,908 to Floyd et al. is directed to a process where a cationically modified polyvinyl alcohol polymer is crosslinked with blocked glyoxal. The crosslinked polymer is then completely dissolved in water and added to pulp material in a papermaking process. According to Floyd et al. the cationic charge is necessary for the polymer to sufficiently retain on the cellulose fibers. The additive reportedly improves the tensile strength and elongation of the paper.

United States Patent No. 3,597,313 to Lyman discloses a wet-end additive for paper products which includes a cyanamide modified polyvinyl alcohol polymer that is partially crosslinked with polyaldehyde. According to Lyman, the crosslinking process renders the polymers thermosetting when heated at temperatures of about 100⁰C. Here also, the crosslinked polymer is soluble in water.

United States Patent No. 6,379,499 to Yang et al. discloses a paper additive for adding dry and wet strength to the paper. The additive includes a hydroxyl-containing polymer, a multifunctional aldehyde, and a catalyst. The catalyst is chosen to promote a reaction between the dialdehyde and the cellulosic fibers.

References of more general interest include United States Patent No. 4,013,629 to Cummisford et al. and United States Patent No. 5,281 ,307 to Smigo et al.

Despite the advancements in paper strength additives, there exists a need for a strength resin that can be conveniently added to a papermaking process in the wet-end to provide improved strength upon drying. As can be seen from the prior art discussed above, polyvinyl alcohol resins were conventionally modified with cationic agents to promote adhesion to the anionic cellulose fibers. Additionally, where crosslinked polyvinyl alcohol was employed, it was subjected to a heating step to solubulize the resin prior to wet-end addition in the papermaking process.

It has been discovered in connection with the present invention that polyvinyl alcohol resin can be effectively added to paper as a strength agent by agglomerating the polyvinyl alcohol particles and combining the polyvinyl alcohol in the wet end of the papermaking process with the pulp slurry. The polyvinyl alcohol particles are retained in the web, by entrapping the larger agglomerates in the fiber matrix, i.e., the particles are retained primarily by mechanical means. Accordingly, the resin does not need to be ionically modified or solubilized by expensive and inconvenient procedures prior to wet-end addition. The method of the invention vastly improves retention of polyvinyl alcohol particles on the fiber mat which enables the use of finer grade polyvinyl alcohol resins that provide high strength to fibrous webs. The above advantages are accomplished using a convenient, cost effective method that is versatile enough to be tailored to a wide variety of papermaking processes.

Summary of the Invention

According to one aspect of the present invention there is provided a method of making a fibrous web having enhanced retention of polyvinyl alcohol strength resin, where the method includes the steps of preparing an aqueous papermaking furnish which includes cellulosic fibers, depositing the furnish on a porous forming support to form a cellulosic mat thereon, and incorporating agglomerated polyvinyl alcohol particles in the cellulosic mat. The cellulosic mat may be dewatered to provide a fibrous web which includes the polyvinyl alcohol resin, where the web exhibits improved strength properties. Among other advantages, the techniques used in the invention are simple, economical, and versatile.

Still further features and advantages of the invention are apparent from the following description.

Brief Description of the Drawings

The invention is described in detail below with reference to the following drawings:

Fig. 1 is a graph showing the tensile strength and 80 mesh retention of fibrous webs prepared with polyvinyl alcohol particles of different sizes;

Fig. 2 is a graph illustrating the tensile strength of fibrous webs prepared at a high shear rate with polyvinyl alcohol strength additives;

Fig. 3 is a graph illustrating the tensile strength and 80 mesh retention of fibrous webs prepared with agglomerated polyvinyl alcohol particles; and

Fig. 4 is a graph showing the tensile strength of fibrous webs prepared at a high shear rate with agglomerated polyvinyl alcohol strength additives.

Detailed Description of the Invention

The invention is described in detail below with reference to numerous embodiments for purposes of exemplification and illustration only. Modifications to particular embodiments within the spirit and scope of the present invention, set forth in the appended claims, will be readily apparent to those of skill in the art.

Unless more specifically defined, terminology as used herein is given its ordinary meaning. Percent, for example, refers to weight percent, or where the context indicates, to mole percent.

The present invention relates to a method for making paper products which includes a wet-end added strength resin. More specifically, the method of the invention improves the strength properties of a fibrous web by combining agglomerated polyvinyl alcohol particles with the paperrnaking furnish. "Agglomerated polyvinyl alcohol particle," and like terminology as used herein, refers to a plurality of individual polyvinyl alcohol particles that are joined together in a cluster, grouping, floe, aggregate or the like. The agglomerated polyvinyl alcohol particles have improved retention in the web, and exhibit superior strength properties as compared to using individual, discreet polyvinyl alcohol particles. The strength resin in the fibrous web includes a polyvinyl alcohol polymer component. As used herein, "polyvinyl alcohol polymer, "PVOH resin," and like terminology refers to polyvinyl alcohol homopolymers and/or copolymers. PVOH resins are derived ftom homopolymers or copolymers of vinyl acetate, by saponification thereof which is well known in the art.

PVOH resins employed in the present invention are predominately (more than 50 mole percent) based on vinyl acetate monomer which is polymerized and subsequently hydrolyzed to polyvinyl alcohol. Desirably, the resins are more than 75 mole percent vinyl acetate derived, more than 95 mole percent vinyl acetate derived, and more preferably are 99+ mole percent vinyl acetate derived. If used, comonomers may be present from about 0.1 to about 50 mole percent with vinyl acetate and may include anionic comonomers such as AMPS or salts thereof, or cationic sites such as amine functional groups. In preferred embodiments, however, the polyvinyl alcohol resin is substantially free of ionic moieties (<0.2 mole percent), and is more preferably nonionic. Other suitable comonomers include glycol comonomers. versatate comonomers, maleic or lactic acid comonomers, itaconic acid comonomers, acrylic comonomers and so forth. Vinyl versatate including alkyl groups (veova) comonomers may likewise be useful. See Finch et al., Ed. Polyvinyl Alcohol Developments (Wiley 1992), pp. 84 and following. The comonomers may be grafted or co-polymerized with vinyl acetate as part of the backbone. Likewise, homopolymers may be blended with copolymers, if so desired.

In general, polyvinyl acetate in an alcohol solution can be converted to polyvinyl alcohol, i.e. -OCOCH₃ groups are replaced by -OH groups through "hydrolysis", also referred to as "alcoholysis". The polyvinyl alcohol used in the invention may have a degree of hydrolysis in preferred ranges of from 95 to 100 percent, from 98 to 100 percent, or from 99 to 100 percent. Representative examples appear in Table 1 below. The degree of hydrolysis refers to the mole % of the resin's vinyl acetate monomer content that has been hydrolyzed.

Exemplary polyvinyl alcohol resins, available from Celanese, Inc. include the polymers 'shown below in Table 1 : Ta le 1: P l vin l Alcohol Resins

¹ 4% aqueous solution, 20⁰C

Some of the above resins are also available as S or SF grades, which are distinguished from standard grades in that they have a smaller particle size. For example, the S grades have a particle size such that 99+% of the product will pass through a U. S. S. 80-mesh screen, and the SF grades have a particle size such that 99+ percent passes through a U.S. S. 120-mesh screen.

The particle size of the polyvinyl alcohol resin powder may be adjusted by grinding techniques, as are known in the art. Preferably, the PVOH powder used as a strength additive in the invention is finely ground. Finely ground PVOH grades are preferred in the invention because the small particles are believed to have a higher degree of swelling upon contact with water, and are more readily solubilized when the fibrous web is dried. Larger particles, on the other hand, may not hydrate as much in the presence of water and, thus, may not ever become soluble when the cellulosic mat is heated. Solubilizing the PVOH while heating the web allows the PVOH to bind the fibers together when the resin recrystallizes. Preferably, the strength resin component has PVOH powder that has a particle size such that at least about 99 weight percent pass through a standard 80 mesh screen. More preferably, at least about 99 weight percent of the polymer passes through a standard 120 mesh screen.

The PVOH resin is contacted with an agglomeration agent to form agglomerated PVOH particles prior to being incorporated in the fibrous web. In general, the location in the papermaking process where the PVOH and agglomerating agents are combined, is not particularly limited. For example, the agglomeration agent may be combined with dry PVOH, with PVOH in a feed tank, with a PVOH slurry in a mix tank, with a PVOH slurry in-line prior to being deposited with the fibers on a forming support, or a combination of the preceding approaches.

It has been discovered in connection with the present invention that the agglomeration agent may be conveniently combined in-line with a PVOH slurry as the slurry is transported to a forming support. In this manner, the PVOH particles achieve suitable agglomeration in the feed conduit after addition of the agglomeration agent, and the agglomerated particles do not need to be subjected to the shear of feed pumps which sometimes can affect the agglomerate particle size.

The PVOH resin is usually allowed to swell by hydrating the powder in water prior to the addition of the agglomeration agent. Preferably, the degree of hydrolysis of the PVOH resin and temperature of the water is selected such that the polyvinyl alcohol particles swell, but do not completely dissolve. The polymer particles may be slurried in water in any amount, preferably about 1 to 20 weight percent. The PVOH particles are typically allowed to hydrate by agitating in water for at least about 30 minutes, and preferably for at least 45 minutes. Alternatively, in some embodiments the PVOH particles may be agglomerated prior to the swelling step.

The agglomeration agent used is water operable, such that it is effective to agglomerate the PVOH in an aqueous medium. As noted above, the agent agglomerates the individual polymer particles into plurality of larger flocculent-like particles. Non-limiting examples of water-operable agglomeration agents may include borax, boric acid, melamine, oxalic acids, and combinations thereof.

Borate compounds, such as borax or boric acid are particularly preferred agglomeration agents of the invention. Borax compounds such as Na₂B₄O₇-IOH₂O or Na₂B₄O₇-SH₂O are suitable. The anhydrous form may also be used. Borate compounds are preferred for use in the invention, because they are operable to agglomerate PVOH in aqueous environments, and are effective even when very small quantities are used. Additionally, it is believed that in the presence of water, the borate compound is in equilibrium with the polyvinyl alcohol particles, and associates them together into floes, but does not form excessively strong interparticle bonding, i.e., the bonds joining the individual polyvinyl alcohol particles are not permanent when water is present. For example, it has been discovered that PVOH agglomerated with borax may dissociate or break-up somewhat under excessive shear, yet tend to reassociate when the high shear is removed. This may account somewhat for the success of the invention, because the weaker bonds allow flocculation, yet do not cause substantial gelling of the PVOH in the water. In addition, it should be noted that since the reaction is in equilibrium, the agglomeration can be reversed by adding more PVOH to an already agglomerated slurry. Accordingly, the amount and size of the agglomerates can be controlled by adjusting the relative amounts of PVOH and borate agglomerating compound. Without intending to be bound by theory, the equilibrium system with borax may be illustrated conceptually by the following equations.

/^OH K₁ /°\ /^OH

P + B(OH)4- ;F=≥ P B- + 2 H2O

O O k2 / \ / \

P B" + P ^=* P B^" P + 2 H2O XOH ^XOH O O

The agglomerating compound may be combined with the PVOH in any form, but may be conveniently provided as aqueous solution where the solution is contacted with the PVOH prior to feeding into the papermaking furnish. The solution may contain agglomeration agent in amounts in suitable ranges of from 0.001 to 5 weight percent, from 0.005 to 2 weight percent, or from 0.005 to 0.05 weight percent.

The concentration of the borate-containing solution and the rate of addition to the PVOH can be adjusted to control the particle size distribution of the agglomerated particles. The agglomeration of the individual PVOH particles increases the effective particle size of the PVOH component, thus enhancing the mechanical retention of the particles in the web, yet still exhibiting the strength advantages associated with smaller particle resins. As noted above, the size of the agglomerates may be controlled by adjusting the relative amounts of agglomeration δ agent and PVOH resin; generally, the agglomerates may have a particle size such that about 30 to 70 weight percent are retained on a standard 80 mesh screen, or from 30 to 50 weight percent, although other agglomerate sizes may be suitable depending on the specific papermaking process used.

Preferably the agglomeration agent is chosen such that the amount of agent needed is minimized, because the presence of excessive agglomeration agent in the furnish can disrupt the papermaking process. On a dry/dry basis, the agglomeration component may be added in amounts of from 0.001 weight percent to about 2 percent of the weight of PVOH, and preferably from 0.01 to 0.1 percent of the weight of PVOH. Accordingly, only a very small amount of agglomerating agent is required to agglomerate the PVOH particles to provide substantially improved retention in the fibrous web. Thus, due to the minimal amount of agglomerating agent required, the invention is extremely cost effective. Indeed, for papermaking processes which already add PVOH as a strength xesin, the added cost is negligible.

Additional factors may also affect the particle size of the agglomerate, such as, PVOH concentration, the mixing energy, mixing time, shear added to the agglomerate slurry, among other factors. These factors can also be adjusted to optimize the particle size distribution of the agglomerated additive, and thus, provides flexibility for different papermaking processes. Generally, the agglomerates should be made larger for webs with larger pores.

The PVOH agglomerates are introduced into a papermaking process. Papermaking processes are diverse, and the type of paper or specific type of process is not limited. The agglomerated PVOH resin is generally combined with an aqueous furnish containing cellulosic fibers. The polymer agglomerates may be combined with the papermaking furnish at any stage in the wet-end of the process, for example, to the thin stock. The papermaking furnish is then deposited onto a porous forming support, such as a wire, cylinder, felt, or the like, where fibers are retained on the support to form a cellulosic sheet or mat. Water is typically removed from the cellulosic mat at this stage by gravity, or by applying a vacuum. The mat may then be transferred onto a felt and passed through one or more presses where it is further dewatered by mechanical means. Finally, the mat is sent to a drying section, where the cellulosic web is usually passed over a series of steel cans that are steam heated. The web may be heated until it has a moisture content of from about 0 to 15 percent.

The heat supplied to the mat during the drying phase of the process helps to solubilize the PVOH resin in the early stages of drying. Additional drying solidifies or recrystallizes the polyvinyl alcohol resin, which acts as a spot weld at contact points between fibers adhering them together primarily through hydrogen bonding and, thus, imparting elevated strength properties to the web. The dryer section typically heats the web up to temperatures of from about 230⁰F to about 300⁰F.

Processing aids, such as release agents, may desirably be used in the papermaking process to prevent the adhesion of the PVOH particles to the dryer surface. The release agent may be applied to the mat surface at the wet press or sprayed onto the mat prior to entering the dryer section. Usually about 3 mg/sqft of release agent is added. Suitable release agents may be commercially available from Sequa Chemical or Buckman.

The inventive method may be used in connection with the production of any type of fibrous web, for example, paperboard, cardboard, corrugated board, wallboard, gypsum facing paper, towel, among others. Additionally, the invention can be used in connection with single ply products or may be used to strengthen multi-ply paper products. The invention is particularly suitable for processes that have poor first pass fiber retention because, in these processes, wet-end strength resin additives also tend to pass through the web. Desirably, the method may be used with process that have a first pass fiber retention of less than 75 %, or even less than 65 %. As used herein "first pass fiber retention," and similar terminology, refers to the weight percent of fibers (dry basis) which retain on a porous forming support. This may be calculated as follows:

_ _, . f Headbox Consistency - White Water Consistency^ , _ΛΛ

First pass fiber retention

where the headbox consistency is the consistency of the furnish prior to contacting the forming support, and the white water consistency is the consistency of the fines slurry which passes through the forming support.

Examples Comparative Data

To determine the effect of particle size on the strength properties of polyvinyl alcohol strength additives, PVOH samples were prepared in the laboratory with different particle sizes. With the exception of the grade that is less than 120 mesh, the samples were produced with different particle sizes in the laboratory by sampling a portion of the polymer powder that remained on a screen of the reported size. Handsheets were prepared from a papermaking furnish with the PVOH additive, and the tensile strength until break was measured on the handsheets. The handsheets were prepared in an 8" x 8" steel forming box which has a screen on the bottom, and a draining mechanism. The papermaking furnish and additive are added to the box, mixed, and then allowed to drain through the screen. The cellulose mat forms on top of the screen, and is subsequently dried until it is substantially free of moisture.

The handsheets in the following examples were prepared using Celvol 165 PVOH strength additive which is ground to various particle sizes. The PVOH additive is hydrated in water for about 45 minutes prior to combining with the paper slurry. The webs are produced with an equivalent of about 50 lbs of PVOH per ton of paper, on a dry basis. The tensile strength of a web with no strength additive was measured for comparison. The retention of each strength additive was also measured by passing the slurried PVOH resin through an 80 mesh screen, drying completely, and measuring the weight percent of the polymer that remains on the screen. The results are outlined in Table 2, below, where the tensile strength values are the average of 8 samples.

Table 2

The results in Table 1 are illustrated graphically in Fig. 1. As can be seen, the strength properties of PVOH additives improve as the particle size of the PVOH decreases. It is believed that the larger particles may not hydrate well enough to effectively solubilize and, in some cases, may actually degrade the tensile properties of the web.

It can be seen from the above results that the finest grade (< 120 mesh) is preferred in these handsheets. However, handsheets do not necessarily emulate commercial processes because handsheets are prepared using a fine screen and under formation conditions which tend to promote the mechanical entrapment of particles. In the following comparative examples, handsheets were prepared as above with 50 Ib PVOH per ton of paper, except that the furnish was subjected to mixing shear at about 200 rpm while draining. This more closely imitates a papermaking process with low first pass retention. As above, the handsheets were prepared with different sizes of Celvol 165 additive. The tensile strength of the resulting webs was measured, and is shown in Table 3, below.

Table 3

The results in Table 3 are illustrated graphically in Fig. 2. In this data set it can be seen that the larger PVOH particles do not appear to add much strength and may in fact weaken the web. Here again, the poor strength of the larger particles is probably due to the fact that the larger particles do not hydrate well, and do not solubilize in the drying section. The 80-120 mesh grade showed excellent strength properties, however, particles of this exact size were only produced in the laboratory by taking a size fraction off of screens, and it is more difficult and costly to produce using grinding methods.

It is noteworthy here that webs prepared with the smallest grade of PVOH exhibited poor tensile properties when present in the web. It has been discovered in connection with the present invention, that while the small PVOH particles exhibit superior strength properties, they are more difficult to retain in the web. Unlike the previous data sheet, the samples in Table 3 were prepared using moderate shear, which effectively agitates the fibers so that less PVOH is entrapped in the cellulosic mat as the PVOH passes through the screen, as occurs in processes with low first pass retention. Invention Data

In the following examples, agglomerated polyvinyl alcohol particles were added to fibrous webs and tested for tensile strength properties and 80 mesh retention. Celvol 165SF (<120 mesh) was hydrated in water for about 45 minutes, and then mixed with a 0.01 % aqueous solution of borax. The amount of borax added to the PVOH was varied to provide agglomerates of different sizes. The agglomerated PVOH slurry was then combined with a papermaking furnish and handsheets were prepared without shear as in examples 1-5 above, where the amount of PVOH is added in amounts of about 50 lbs per ton of finished paper (dry). The tensile strength and retention data is outlined in Table 4, below.

Table 4

The data in Table 4 is shown graphically in Fig. 3. As can be seen above, the 80 mesh retention increases as more agglomerating agent is added, indicating the presence of larger agglomerates. Additionally, it can be seen that for these webs, the tensile data peaks when about 0.019 wt. % of agent is used, and declines thereafter. This is perhaps because if the agglomerates are made larger, they also become fewer in number; thus, the strength additive may form fewer "spot welds" between the fibers. Optimal agglomerate size may vary from process to process, and in some papermaking processes it may be desired to add more or less agglomerating agent.

Here again, although the PVOH particles alone (no agglomerating agent) appear to exhibit good results, the handsheets in this data set were prepared using low or no shear, and thus, the result is higher than one would expect on a commercial process. In the following examples, agglomerated PVOH additives were further tested for strength properties by forming handsheets with moderate shear (mixing, 200 rpm) to emulate a process with low first-pass retention. The agglomerated PVOH additive and handsheet were prepared with applied shear as described above in examples 6-10, with a target amount of PVOH of about 50 lbs per ton of paper. The tensile strength results are shown in Table 5, below.

Table 5

The results in Table 5 are shown graphically in Fig. 4. The data in Tables 4 and 5 illustrate that the small particle PVOH resins can be effectively retained in a fibrous web by forming agglomerates of the particles. Comparing Example 10 and Example 18 which have the same particle size, it can be seen that by using a small amount of agglomeration agent, the strength properties of the web are improved by about 30 %.

Additionally, the above results illustrate the versatility of the invention because, by varying the amount of agglomerating agent and PVOH, agglomerates with various sizes may be produced depending on the needs of a particular papermaking process. For example, as can be seen in Fig. 1, small particle PVOH grade has an 80 mesh screen retention of less than 30 %. Fig.3 illustrates that the invention enables the use of a wide range of agglomerate particle sizes; for example, the addition of only a small amount of borax produces agglomerates that are sized such that they exhibit an 80 mesh screen retention of more than 80 %. While the invention has been illustrated in connection with several examples, modifications to these examples within the spirit and scope of the invention will be readily apparent to those of skill in the art. In view of the foregoing discussion, relevant knowledge in the art and references discussed above in connection with the Background and Detailed Description, the disclosures of which are all incorporated herein by reference, further description is deemed unnecessary.

Claims

WHAT IS CLAIMED IS:

1. A method of making a fibrous web which includes polyvinyl alcohol resin as a wet-end strength additive, said method including the steps of: a. reacting polyvinyl alcohol (PVOH) resin with a water-operable agglomeration agent to form a plurality of agglomerated PVOH particles; b. combining the agglomerated PVOH particles with an aqueous papermaking furnish that includes cellulosic fibers; c. depositing the papermaking furnish on a porous forming support to form a cellulosic mat thereon, such that agglomerated PVOH particles are retained in the cellulosic mat; and d. dewatering the cellulosic mat to produce a fibrous web that includes the polyvinyl alcohol resin.

2. The method according to claim 1, including the step of heating the cellulosic mat such that the polyvinyl alcohol resin in the mat first solubilizes, and then solidifies upon further drying.

3. The method according to claim 1, wherein the agglomeration agent is a borate compound.

4. The method according to claim I₅ wherein the agglomeration agent is borax.

5. The method according to claim 1, wherein the amounts of PVOH resin and agglomeration agent are controlled to provide agglomerated PVOH particles which are sized such that they exhibit a retention on a standard 80 mesh screen of about 30 to 70 weight percent.

6. The method according to claim 1, wherein the amounts of PVOH resin and agglomeration agent are controlled to provide agglomerated PVOH particles which are sized such that they exhibit a retention on a standard 80 mesh screen of about 35 to 50 weight percent.

7. The method according to claim 1, wherein the polyvinyl alcohol resin has a particle size such that at least 99 weight percent passes through a standard 80 mesh screen.

8. The method according to claim 1 , wherein the polyvinyl alcohol resin has a particle size such that at least 99 weight percent passes through a standard 120 mesh screen.

9. The method according to claim 1, wherein the polyvinyl alcohol resin has a degree of hydrolysis of at least about 95 percent.

10. The method according to claim 1, wherein the polyvinyl alcohol resin has a degree of hydrolysis of at least about 98 percent.

11. The method according to claim I₅ wherein the polyvinyl alcohol resin has a degree of hydrolysis of at least about 99 percent.

12. The method according to claim 1, wherein the polyvinyl alcohol resin has a characteristic viscosity in the range of from 40 to 100 cps.

13. The method according to claim 1, wherein the polyvinyl alcohol resin has a characteristic viscosity in the range of from 50 to 80 cps.

14. The method according to claim 1, wherein the polyvinyl alcohol resin is not amine functionalized.

15. The method according to claim 1, wherein the polyvinyl alcohol resin is substantially free of cationic moieties.

16. The method according to claim 1, wherein the polyvinyl alcohol resin is not modified with ionic groups.

17. The method according to claim I₃ wherein the polyvinyl alcohol resin is present in the fibrous web in amounts of from 5 to 100 lbs per ton of web, on a dry basis.

18. The method according to claim 1, further comprising the step of incorporating the fibrous web into a multi-ply paper product.

19. A method of making a fibrous web including the steps of: a. reacting polyvinyl alcohol resin particles with a borate compound to agglomerate the polyvinyl alcohol resin particles, where the polyvinyl alcohol resin has a degree of hydrolysis of at least about 95 %; b. incorporating the agglomerated PVOH resin in an aqueous papermaking furnish that includes cellulosic fibers; c. depositing the papermaking furnish on a porous forming support, to form a cellulosic mat thereon, such that agglomerated PVOH resin is retained in the cellulosic mat; and d. dewatering the papermaking furnish to produce a fibrous web which includes the polyvinyl alcohol resin.

20. The method according to claim 19, wherein the borate is provided as an aqueous solution having from 0.01 to 2.0 percent of the borate compound.

21. The method according to claim 19, wherein the borate is provided as an aqueous solution having from 0.05 to 0.5 percent of the borate compound.

22. The method according to claim 19, wherein the polyvinyl alcohol resin particles are reacted with the borate compound in a feed conduit while concurrently being transported to the forming support.

23. In a papermaking process having a first-pass fiber retention of less than 75 percent, and including the steps of preparing an aqueous papermaking furnish which includes cellulosic fibers, depositing the furnish on a porous forming support to form a cellulosic mat thereon, the improvement comprising the steps of: a. slurrying polyvinyl alcohol resin powder in an aqueous medium, where the polyvinyl alcohol resin has a degree of hydrolysis of at least about 95 percent; b. contacting the polyvinyl alcohol slurry with a water operable agglomeration agent to form a plurality of agglomerated PVOH particles in the slurry; c. combining the PVOH agglomerates with the aqueous papermaking furnish; d. depositing the papermaking furnish on a porous forming support to form a cellulosic mat thereon; and e. dewatering the cellulosic mat to provide a fibrous web which includes the polyvinyl alcohol resin.

24. The improvement according to claim 23, wherein the polyvinyl alcohol resin powder is allowed to hydrate in the slurry for at least 30 minutes prior to agglomeration.

25. The improvement according to claim 23, wherein the polyvinyl alcohol resin powder is allowed to hydrate in the slurry for at least 50 minutes prior to agglomeration.

26. The improvement according to claim 23, wherein the temperature of the PVOH slurry is controlled to be less than about 120⁰F.

27. The improvement according to claim 23, wherein the temperature of the PVOH slurry is controlled to be less than about 100⁰F.

28. The improvement according to claim 23, wherein the temperature of the PVOH slurry is controlled to be from 6O⁰F to 100⁰F.

29. The improvement according to claim 23, wherein the polyvinyl alcohol resin powder is slurried in water in amounts of from about 1 to about 20 weight percent.

30. In a papermaking process including the steps of preparing an aqueous papermaking furnish which includes cellulosic fibers, and depositing the furnish on a porous forming support to form a cellulosic mat thereon, the improvement comprising the steps of: a. preparing an aqueous dispersion containing a plurality of agglomerated PVOH particles; and b. incorporating the agglomerated PVOH particles in the cellulosic mat.